I'd like to ask you, fellow GOGers about your experience with GOG games which are wrapped with ScummVM emulator.

For example, I've bough Legend of Kyrandia 2 recently which uses this emulator. I run Linux and this game is listed Windows only, so I copied the game files and run ScummVM version 2.0.0. Since starting the game there are all sort of strange bugs. Speech of characters is the most infuriating one. After one person finished speaking (subtitles on), there is a 2second pause until other speaks.
Other example is the color puzzle in the swamp. After finishing it, there is a tune with half of it missing in the scummVM.

I've downloaded cd version of the game and tried to run it in pcem. There is no such behaviour.

I've checked the compatibility page in scummvm and this game is listed only as good. I'd love to ask support about this, however since I'm running Linux I don't know if it is only my issue. Can someone with Windows try to remember if there was such issue, or try it?

I can't test anything, but here are some generic answers/guesses that can be worth checking.

Pauses with speech: have you tried to change game speed settings in ScummVM? It sounds to me that this could be the kind of problem where the text speed is set too slow.

Music issue: sounds like a bug. There are some midi-related bugs that are known.
http://bugs.scummvm.org/query?status=!closed&game=Kyrandia+2

Once again, you may want to try some other settings in ScummVM to see if this happens only with certain settings. Also remember that there are global settings and game specific settings that override global settings.

And while ScummVM really is the best way to play adventure games, it sometimes has some very strange bugs. I once encountered a bug in Tony Tough where a puzzle was unsolvable, until I temporarily reduced color palette, passed the puzzle, and then reverted the settings after which there were no issues.

You might want to try an unstable test version too. When I played Rex Nebular the game had distorted colors, but playing it with an "unstable" version fixed the issue.
http://buildbot.scummvm.org/builds.html

Also, ScummVM is not an emulator, which is in many cases root cause for an unexpected behavior.

I've found some setting in ScummVM for the subtitle speed, but when I've set it to 0 or 255 it was all the same, so that's probably not it.

With the support of this game not perfect, I wonder why GOG went with this route, instead of the DOSBOX?

I doubt you're going to get support for running a game in Linux, unless its listed as supported and you're using the ScummVM that GOG bundled along.

That said ScummVM has always worked great for me if it wasn't an experimental title and my expectation would be a well-working game.

I played (and completed) the first 2 books in the Kyrandia series back in 2016 using ScummVM on Linux and I experience none of the issues described.

According to my logs (Book I, Book II), I did use ScummVM v1.6.0 and v1.7.0. You could try downloading these older versions and see whether there's been any regression in v2.0 that causes those undesired effects.

The same could be said about GOG release of Lure of the Temptress - ScummVM implementation of the sound module for Adlib is broken beyond recognition and doesn't sound at all like in the original (or, indeed, how it sounds under Dosbox emulation). Nevertheless it bundles with ScummVM...