The great things about nootropic stacks is that often they are natural substances. Of course, some natural substances can be harmful, but generally you can be pretty lax in analyzing substance mixing as the odds of adverse effects are much lower than they would be if you were mixing pharmaceuticals (ignoring the modafinil) that you didn't know about.
As for the rhodiola, this can help reduce the caffeine/modafinil irritability (may want to look into this more though as some people have reported mixing modafinil with other stimulants actually makes them relaxed while still being focused), however sometimes rhodiola is known to cause severe stomach pain. I imagine having stomach issues all day could negate the benefit of being less irritable, though if this does happen to you, it may go away after a week or two.
Are you positive though that it's the actual mixing of modafinil and caffeine that brings on your irritability, though? I find that, in general, when you use something like modafinil (or caffeine, for that matter) which really gets you focused, driven, and more apt to increase your productivity, this also brings on some impatience. I assume you mean you are irritable in your interactions with others, and remember that interactions with others require you to slow down and go at their pace, yet being impatient and driven from the modafinil can make these situations irritable. This may be something you need to deal with mentally that can't easily be fixed by adding more to your stack.
Also, I would recommend something other than the NutriGold for bacopa. Check out some reviews on various brands online and you'll find some more ideal alternatives. Also feel free to visit ModaMind for any replenishment to your modafinil. We've been shipping pharma products reliably for 14 years.