I like big buffs to the forge and workshop; they are a good way for rewarding large city specialization. But 50% is far too much of a buff. I think the 50% military buff on the arsenal is also too much. Increasing the vanilla values by a factor of 1.5 is a good start in general, but I think the more-than-doubling is too much. I don't think you should think of this as a 20% increase in total hammers, I think you should think of this as doubling the increase from the building. If in vanilla it was worth building at 15 hammers, now its worth building at 8 hammers, which is almost every city you have. It should not be the design goal to make every building worth having in every city. With the military unit production, you're ignoring the synergy benefits you can get from using gold to buy and stack up all the XP-yielding boosting buildings and then all the production boosting buildings in a single city, and producing massively experienced units very very rapidly. When you add big boosts to early buildings like the forge and workshop and windmill, you also end up indirectly nerfing the factory. Factories should be a huge deal; they should make coal important, and they should be a large production boost at an efficient build cost.