Obviously something needs fixing.

The square should shoot. That makes infantry a little too strong, as cavalry could beat a square if determined enough. That's just plainly impossible now. However it is equally easy to avoid the square and just bypass it for some juicy artillery or generals. That should be punished by flanking shots and rearshots by the square as the cavalry passes by.

So let them shoot all round, but tone down the offensive bonusses against cavalry in melee.