When I change my game's format to R6 from R15 it comes up with something of what i believe is a animation error. https://kapwi.ng/c/8lr2O5y2
Of course it's going to be an error. r15 and r6 are completely different and incompatible animation types.
r15 animations have more limbs involved, causing r15 animations to be completely incompatible to r6 rigs. You would have to make new animations using a r6 rig instead.