Sorry you're having such a frustrating time with the difficulty.
This is certainly something that can be adjusted downward if we find the balance is really out of whack. Levels where the game likes to dish out unwinnable scenarios are the top priority here, in particular.
Regarding level 20, I just tried that one 13 or so times and was able to complete it each time. What, in particular, was causing you to lose here? Clearing too many reds or stacking blocks above the board? If the latter, was it because of tinder blocks you simply could not clear? There are a lot of tinder blocks on this one (~19% of the blocks are tinder), but this should be balanced out by the number of red and white blocks (~23% and ~10.5%, respectively, while normal blocks are ~9.5%). Lowering the amount of tinder and the number of reds and whites, to compensate, might work, but I'm not positive that that would make the stage any more winnable. It might also extend the amount of time this stage takes significantly, which is something I often tried to avoid doing when making stages. When playing this stage, I recommend keeping whites around; they're great for using in emergencies (you're about to lose, so you use them to clear some blocks that will make tall columns shorter), for positioning reds by clearing blocks of other colors, or clearing with reds to help clear tinders. Using them for other purposes is largely wasting them. They're really the key to this level, I think.
Regarding 22, the score limit could probably stand to be higher, yes. As it is right now, you're allowed a couple of missteps (doing just chains of 3 without any errors, I ended with 1244 points. A 2-deep chain of 3 is worth 180 points instead of the usual 60, so you could do 2 of those, or several chains of 4 (100 points each)), but that might be a bit harsh this early.
The skills taught in this stage (avoid large chains, avoid combos) are very helpful for later in the game, where there are many stages that require very careful playing to ensure you don't have large chains or large combos or streams hitting wrong blocks. It's sort of the opposite of what you normally have to do in this game, so you have to untrain yourself from how you normally play the game when doing these sorts of stages. Some helpful tips for this stage: try to avoid white blocks, since they double the score for the current chain, and try not to add too many unnecessary blocks to the board, since each one gives you a point. If you've made a few mistakes, those points can put you over the edge. As for the white block thing, that's non-obvious enough that white blocks probably shouldn't be present in this stage at all. I expect them to be removed in the future.
For 28, I think this one is okay currently. When dealing with sun and moon blocks, you need to realize that you can try to balance out the number of each block based on how you make your chains. If you have too many moon blocks and not enough sun blocks, you want to try making moon->sun->moon chains, and you can also use double-arrow sun blocks to have a moon shoot a sun, which then shoots two moons. Level 28 should be roughly balanced between sun and moon blocks, though; if you're seeing a wild imbalance, it may be related to how you're making chains.
Level 29, on the other hand, intentionally has way more moon blocks than sun blocks (~10.7% for sun blocks, and ~25.3% for moon blocks). It's a level about conserving this limited resource, so those tricks I just discussed for level 28 are necessary here. With them, you should be in good shape, but this can definitely be a difficult level.
If you feel a level's particularly borked and you'd like to make a balanced version for yourself that you can suggest be included in the game, try it out in the game's level editor. Levels are located in the Official Brainteasers folder. If you do this, though, I recommend making a copy of the level first before you go tinkering it so you have a spare around. You can make a copy by going into the "RuntimeData\Logic\LevelFolders\Levels For Tidalis Main Story" in a file explorer program and copying the level there (that's the same folder as Official Brainteasers. The different name in-game is to make it clear that this is where brainteasers are played, for those who want to play brainteasers without finding them in the adventure mode). Also, posting about the levels you find to be unbalanced is definitely helpful and I hope you continue to do it.
