Dear devs, any chance of Steam achievements added at a later date?

I just finished the last puzzle shown on the path selection screen ("The Light"), and it certainly appears that this was the last puzzle. However, at the top of the screen, it says "85 / 87 Solved". I went through the path from left to right and counted, and there are only 85 puzzles displayed. Am I somehow missing puzzles (and there really are 87) or is that "87" a typographical error (and there are only 85)?...

I can't find the last two puzzles. Are there more puzzles, or is the counter just bugged?

When I turn the music and sounds off in the settings, they don't always stay off but the music starts playing in the beginning of some levels...even if on the settings it shows that it should be off, so I need to turn it on and again off...