An alternative could be to make it so the golems have X% of breakin down every turn and that X% increases for every feature you add. (I'm not goin to put a value on X, so jus deal with it. But for simplication purposes, assume that X=100. That makes it easier to get percentages.) So, to lay it out, your golem starts with no features and 0.1X% chance to break down. Then, with one feature, your golem has a 0.2X% chance to break down. With 3 features, that goes to 0.3X%. With 4, it jumps to 0.4X%. With 5, it jumps to 0.45X%. And it stops at 5. You can still add features, but it won't increase the chance of breakin down.
Of course, you could have a promotion called "Golem Repair", which would have 3 levels. So, you'd have "Golem Repair I", "Golem Repair II", and "Golem Repair III". (Needs a better name prolly than "Golem Repair", somethin to kinda imply that there's a Luchiurp repairmen with the golem; kinda like the Flagbearer promotion for Warhammer, if anyone's familiar with it.) These promotions reduce the chance that the Golems will break down. So, "Golem Repair I", which will require 2 features, will reduce the chance of a breakdown by 0.1X%. And "Golem Repair II", which requires 3 features, will reduce it by 0.3X%. Lastly, "Golem Repair III", which requires 4 features, will reduce it by 0.4X%. So, provided you're smart and decide to pick the "Golem Repair" promotions, you should rarely, if ever, have your golems break down.
The only question is...will the AI be able to handle it? Possibly.