About the cooldown idk maybe just unbalancing then ? O nearly never witness when the node worked but only when they didn't work while I thought they would, that may be just me or a UI understandability problem maybe? I'll be honnest I can't be sure but what I'm sure of is that the cooldowns felt like "no you're not gonna do what you want" x)
Maybe I'd prefer slower attack rate and more tanky ennemis but cooldowns that would be only for some powerful nodes. Thx for the reply btw (how did you manage to do this in 5 days TvT?).