Do you use a crossbow ? I think the 5 AP for crossbow use is 'stronger' than the 4 for the spell.
You either need to put the file into Data\Public\Main\Stats\Generated\Data and maybe Data\Public\Shared\Stats\Generated\Data might work as well. But the game does not know about a path ...\Changes\... and thus will not read the file.
You would have to create a mod with the Divinity Engine and you could call this mod 'Changes' if you like, but the path then will look something like Data\Public\Changes-<some-combination-of-numbers-and-letters-called-UUID>\Stats\Generated\Data.
If you create a mod, the editor assigns a UUID to the mod and creates a directory which contains the name of the mod and its UUID. If you activate this mod, the game reads all stuff from this mod directory first before reading all the rest.
You can still do the 'easy way' and put your changes into two of the directories known to the game by default, the two mentioned above. In this case you might have to rename the file MainLSF.pak. There are a couple of threads on this topic and the mod 'Scales' is one of those that require renaming MainLSF.pak I think. You could look into it's README or installation instructions on Nexus.
