Might be a minor thing but I wondered what the item flag (item_flags.csv) countable actually means. It seems hard to misunderstand but if it really means items that can have a count of how many there are, the data is quite bad on this.
As example: all pokeballs are countable but berries are not. Actually most items that have a count in the games are not flagged as countable.
I wonder if there is a special reason for it or if nobody bothered setting it because almost everything can have a count anyway. The only items that are non-countable are actually key and story items with special purpose like the bike.

Would it not make more sense to change this to a non-countable flag and only mark these "few" items with it?
I know TMs are a bit more complicated on this since it depends on the generation if the item is unique or can have a count but since TMs are a bit special anyway this shouldn't be a reason to not correct this.