Realize no system can overcome improper ducting sizing. It’s very possible the original design is the bottleneck. You adding a massive amount of heat and moisture is just exasperating the issue. You’ve got a unique setup. What it sounds like is that the HVAC sales person didn’t do a great job of explaining what is possible with your system and setup. There are limits and oversizing equipment (even if it fits in the closet) doesn’t = giving you more cooling power. Ducting affects how the house cools a lot more. Honestly, your particular setup would’ve benefited greatly by a hybrid system of air conditioner properly sized /with/ a mini split system for your grow area and server farm specifically. That probably would’ve helped.