Huseyin is complaining about cavalry being too OP and the stables are helping his opponents to spam out cavalry too quickly, therefore in order to resolve this problem from the root we must first NERF cavalry units in general, then consider changes to stables.
The acceleration mechanics of A26 will be a blow to the strength of cavalry, so I believe this part of the problem will be fixed. Furthermore, we can decrease the attack value of javlin cavalry to 16, equal to their infantry counterparts. If Huseyin is discontent with spamming stables, then perhaps we can raise the stone cost to 100, identical to a that of a barrack. I cannot understand why the stables should be any cheaper than barracks or vice versa.