1) Well, I'd like it to use my mp to cast heals, until I'm out of mp, and not deliberately restore mp unless it's cost/item-effective for more heals (or is below the mp restore setting in mafia, of course). This seems to be the way it works in mallmode, but in my (admittedly limited) experience, it doesn't seem to work that way in non-mallmode.
2) It most definitely is in mallmode for that quote (at least, it bought stuff from the mall on its own initiative). I wasn't clear before: the mentioned episode of "overhealing mp using a mixed restorative" occurred when I wasn't in mallmode, but the quoted episode of "overhealing hp using a mixed restorative" occurred just a few hours ago, when I was in mallmode. They may be totally unrelated quirks, for all I know.
I ran a diff against a fresh download of Universal_recovery, and found a change that I couldn't understand why I made, so I replaced my recovery script with the fresh download, and ran mafia until it happened again (and neat, I now have additional price information showing up):
Restoring HP! Currently at 147 of 246 HP, 18 of 221 MP, current meat: 7515656 ... Target HP = 222.
In mallmode, best HP restorative is: gauze garter @ 127.5 meat total.
In mallmode, best MP restorative is: ancient Magi-Wipes @ 180.0 meat total.
Mall price to restore 24MP is 79 meat.
Cast a healing skill.
Casting Disco Power Nap 1 times...
You gain 40 hit points
Disco Power Nap was successfully cast.
Restoring MP! Currently at 187 of 246 HP, 6 of 221 MP, current meat: 7515656 ... Target MP = 12.
In mallmode, best MP restorative is: ancient Magi-Wipes @ 19.636364 meat total.
Trying to use 1 ancient Magi-Wipes
Using 1 ancient Magi-Wipes...
You gain 56 hit points
You gain 51 Mojo Points
Finished using 1 ancient Magi-Wipes.
Current HP: 243, MP: 57
My meat: 7515656. Should be successfully healed...
Casting Disco Power Nap 1 times...
You gain 40 hit points
Disco Power Nap was successfully cast.
Current HP: 246, MP: 45
My meat: 7515656. Should be successfully healed...
This occurred directly after a mafia-directed combat. I do, in fact, have my health recovery set to recover up to 90%. I'm fighting in an area with monsters that can 3-shot me, and I'd rather heal out of combat than in combat. That magi-wipe would have been perfect, if it hadn't then tried to cast the heal.
3) Well, my initial assumption would be that obeying mafia's preferences would mean just not buying from the mall. I'm fine with buying the heal items myself; in fact, I prefer it. But having it use completely different logic instead was unexpected. If I had known there was normally a mallcore notification in the CLI, I'd have been suspicious much earlier, but to be honest, I didn't even remember that mafia setting until I saw the script comment. I'll definitely make the change you suggested, as it will behave exactly how I'd like it to.