How are they both in "stealth", whatever that is, and have darkness up without being noticed/located within a 20' radius. If the darkness moves, at all, you can figure out exactly where the bad guy is.
Counterspell has a range of 60' and targets the caster, so unless your max range spellthrowers have closed the distance, they aren't counterspelling anything the party does. If they are close enough to counterspell, the party options have drastically improved.
But, let's go back to the 'stealth' thing. Looking at your build you have a +4 dex, +6 proficiency in stealth, have apparently taken the skill feat from XGtE to gain proficiency in this skill for a +16 bonus to stealth. I assume you're absolutely joking about the Pass without Trace spell, right? You aren't locking in your concentration slot for that spell AND have all of these other spells, like Enemies Abound and Darkness up, right?
Basically, the action economy for your uber build is broken. You cannot actually have all of the necessary counters up all the time.