The function call to MiscGameplayFunctions.RemoveSplint in DeactivateCondition of BrokenLegsMdfr should be moved to OnDeactivate where it logically belongs.
It makes adding additional Splints terrible in the sense that static functions can not call super and therefore a whole complete level of checks needs to be built in DeactivateCondition of the modifier to prevent the function being called or the player will always end up with a vanilla splint in their inventory.

Since playermodifiers got some additional love in 1.14 this might as well be corrected at the same time.