So again,it upgrades Wolf to 43 health(max) from 40 and speed,but also upgrades jump strength to funny numbers and still doesnt upgrades wolf attack at all,stop after fully upgrading wolf jump strength to 0,66 from 0,42(it should upgrade it just once,because it doesnt grants wolf further leap,instead slows down on getting up and speed can be left as is,its just for some reason doesnt upgrade attack damage and it probably should upgrade health a bit more,somewhere to 46 - 48)
I guess it can be happening because it primarly upgrades only horse stats,and horse dont have attack

Footage of how funny jump stat gets

Okay, so a better method is going to be an entity- or tag-specific data map that lists the eligible attributes for that mob to prevent non-horses from having their jump height strengthened so much.

Still happens,but now there is also either visual bug or just plain bug with not adding up to nothin'(probably it actually tries to add to attack but fails)

latest.log
debug.log