ToME: the Tales of Maj'Eyal

If you learn 1 talent level of channel staff/psiblades from an escort, and then buy staff combat/mindstar mastery from angolwen/zigur, the talent tree level will be stuck on 0.8 mastery.

This is an old, known issue, not specific to Git, and it's not really clear how to fix it, except for maybe forcibly setting it at 1.0 mastery.
However, then you can eat your cake (have psiblades talent before you haz moneyz) and have it (still buy 1.0 mastery), so I personally like this punishment for impatience. From an in-game perspective, you could say that quick-and-dirty, improper way of doing things you picked up from escorts is holding you back when you try to learn properly.
Do you also mean "accepts no more catpoints" by "stuck"? Then it's probably a bug.

You can get an alchemist escort before you can amass 100 gold to get the locked tree, so there is no "punishment" here that makes any sense. It also forces you to be spoiled to get the optimal result which is something ToME tries to get away from.

This "punishment" will make no sense to players, and there's no way to know in advance without checking outside knowledge. Thus, it should be avoided.