Good points. Colemak was optimized for English; it seems to me to work surprisingly well for other latin languages but not optimally for germanic ones (Dutch isn't so nice according to a user). For my own language Norwegian, I notice a few minor problems such as KJ, but they're nothing bad. With practice one learns to devise techniques for such road bumps; for instance, the KJ bigram I write using the middle finger on J which works rather nicely!

My main point though, it that I write a lot of English each day. And I certainly don't want to learn two layouts! So Colemak works well enough in Norwegian and perfectly in English and that's what I want.

The problems with Dutch are mostly combinations with "J", which is much more common in Dutch than in either English or German.
je / jij / jou / jouw (you / your), ja (yes), ...

Interesting, I would never thought that index overloading will concern Czech, because letters frequency really differs of German or Dutch, and are, to my mind, quite acceptable; maybe it is indeed due to a “bad” typing technique (or short fingers, or misjudgment on my side). As for “kolik”, words with K are “bad examples for QWERTY because the position of K on the “home row” is a joke regarding common anglo-saxon or latin languages (En, Fr, Es, Pt, De), but with a little training of few tries, I found it almost faster (not more confortable, that is truly tricky) to type with Colemak than with QWERTY; concerning JE (I'm concerned because of French), the problem comes too from the non-orthogonality of the keyboard, I invite you to try a more ergonomic keyboard (TypeMatrix is a good and affordable example), it can be truly beneficial !
Thank you very much for your contribution :) (first time I speak to a Czech \o/)

Any other experience ? I still have no German ^^'

I hope some Germans will show up :)

This website tells me this:

GERMAN
Order Of Frequency Of Single Letters: E N R I S T U D A H G L O C M B Z F W K V P J Q X Y
Most Common Digraphs:  en er ch de ge ei ie in ne be el te un st di un ue se au re he it ri tz
Most Common Trigraphs: ein ich den der ten cht sch che die ung gen und nen des ben rch
Common Two-Letter Words: ab, am, an, da, er, es, ob, so, wo, im, in, um, zu, du, ja ab

Using Juli16 for German:

- German and Dutch are similar, but the U is much more used in German. It's location may be suboptimal
- digraphs and trigraphs (my assessment).  Easy = bold. Normal = normal, Hard = italic 
Most Common Digraphs:  en er ch de ge ei ie in ne be el te un st di un ue se au re he it ri tz
Most Common Trigraphs: ein ich den der ten cht sch che die ung gen und nen des ben rch
Common Two-Letter Words: ab, am, an, da, er, es, ob, so, wo, im, in, um, zu, du, ja ab

For Dutch, it is slightly better. Yet, depite this, even for German, Juli16 scores better than Colemak, Dvorak and all other layouts in Patorjk. I compared in Patorjk Juli16 to the layouts Colemak, Dvorak and Balance 12 (which is a very good layout). For various languages. These are the winners.
For Italian: winner is Juli16
For German: winner is Juli16
For French:winner is  Juli16
For Dutch: winner is Juli16
For spanish: winner is Balance12,  # 2= Juli16 #3/#4 = Dvorak or Colemak
For English: winner is Balance12,  # 2= Juli16 #3/#4 = Dvorak or Colemak

In case your interested, some stats for Juli16 on my corpus:
Left hand: 57% - Fingers: pinky 9% ring 10% middle 22% index 16%
Right hand: 42% - Fingers: pinky 8% ring 10% middle 12% index 14%   (I am righthanded by the way; the layout is a bit skewed to the left, but not problematically so).
Inward rolls:7.5%; Outward rolls: 2.9%
Same hand:36.4%; Same finger:1.5%;
Row change:12.3% Home jump: 0.7%  (home jump is on a qwerty board for instance iec or mu

For comparison, here is Colemak (on an English corpus!) :
Left hand: 46% - Fingers: pinky 8% ring 7% middle 11% index 18%
Right hand: 53% - Fingers: pinky 9% ring 10% middle 15% index 18%
Inward rolls: 4.6%; Outward rolls: 2.5%
Same hand: 42.6%; Same finger: 1.9%
Row change: 18.6%; Home jump: 1.3%

And here is Dvorak (on an English corpus!)
Left hand: 44% - Fingers: pinky 8% ring 8% middle 12% index 14%
Right hand: 55% - Fingers: pinky 11% ring 13% middle 13% index 16%
Inward rolls: 4.1%; Outward rolls: 1.3%
Same hand: 31.1%; Same finger: 3.2%
Row change: 14.4%; Home jump: 0.5%

So, my layout scores better on distance (not included here); has more rolls than Colemak and Dvorak, lower row change than both, lower same finger than both. The alternation (same hand stat.) is between Dvorak and Colemak. Dvorak favors left-right, left-right (LRLR etc), my layout favors LLRRLLRR etc. Dvorak does best on home jumps: very low. Mind that the Colemak and Dvorak stats are done with and English corpus (for which they are optimized), my stats are done with a 85% Dutch corpus, for which it is optimized. When Colemak and Dvorak are "fed" with Dutch text, they will score worse, and the gap with my optimized layout will be larger.

One of the problems for me with Colemak is the placement of D, H, G and J => index finger overload in Dutch. Dvorak is better, but has the I and D, and to a lesser degree the G, wrong. Plus, LRLRLR is too much alternation for me. Juli16 has very nice short rolls in Dutch: en ne ie ei dr tr st ts bl ou

To be perfectly clear (I am on a Colemak forum after all ;-) : Dvorak and Colemak are both way better than Qwerty, also for Dutch and German. If you don't want to go the "custom layout" route, please try both Colemak and Dvorak and pick the one you like best.

I'm wondering how you determined this (I don't think my own analyses ever were able to detect such things).

LLRLLRLLRLLRLLRLLR is an example of 33% same-hand, and yeah, LLRRLLRR would be 50%.  (On the other hand, so are LLLLLLLRLRLRLRLRL and LLLLLLLLLLRLRLRLRL respectively.  This is another reason same-hand percentage is not a very insightful measure.)

A good way to make a general analyzer might be to take patterns (e.g. LLRR, RRLL vs LRLR, RLRL) as input and just count the number of occurrences.  I'm not 100% sure we'd be able to interpret this data as "one tends toward LLRRLLRR and the other toward LRLRLRLR", but it'd be a start.

I haven't had time to update any of my analyzers, unfortunately.  Feel free to try your own hand at one.

General thread point: still keeping an eye out for good (and preferably large, representative) sample texts/n-gram stats for non-English languages.

Regarding the analysis, indeed: counting LRLR etc patterns, and calculating percentage perhaps? I'll chew on this!
I was thinking of a different solution: giving letters a value. The value of the bold letter is calculated as a function of the letters that surround it (I ignore the first and last letter of the text for now. Also: spaces don't count) 

LRL -> 2  (R is surrounded by 2 L letters)
LRR -> 1 (R is surrounded by 1 L letter)
RRL -> 1 (R is surrounded by 1 L letter)
RRR -> 0 (R is surrounded by 0 L letters)

same thing for the Ls. 

Next, sum the numbers and divide by the total number of letters in the text. In a 1x1 text, every letter will have value 2. So, the mean value (total/#letters) is 2.  So, 2 is maximum alternation.

In a 1x0 text (all Ls or all Rs), all letters will have the value 0. Mean is 0 as well. So 0 = no alternation at all.

In a 2x2 text, every letter will have an L and an R as neigbour, so every letter has value 1. Mean is 1 = 2x2.

Let's take a 3x3 text.  LLLRRRLLLRRRLLLRRRLLLRRR. Ignoring the starting and finishing letter, the values are 011011011011011 etc. Mean value is (0+1+1)/3 = 0,67.

Finally, 3x1x1x2. This one is irregular (no fixed rithm) and imbalanced: the left hand has 3 + 1 = 4 strokes, the right hand has 1 +2 = 3 strokes.  Again, ignoring first and last one.  LLLRLRRLLLRLRRLLLRLRRLLLRLRR  This gives 012211121221 1012210121221 = 32 / 28 = 1,14

I'm not happy with this yet, because irregularity does not show in the metric..... I'll think some more. Anybody else has a betetr idea? Feel free to critisize, improve, or steal !