If you place the MODS deck in the last slot (closest to edge of box) it looks slightly wider and might avoid the bulging walls issue? If you look closely at the picture on Folded Space packaging you can see the green cards of the MODS decks seems to be in that spot for a reason.

Jeeeesus those tokens are GORGEOUS but $130?!?!?!? No thank you good sir

If you use wood glue or pva, when ot presses out the bottom of the sides, spread it along and its seemless. I always use folded space, price, practically and weight tbh. They often allow room foe expansions too

I just picked up this insert at Pax Unplugged. I enjoy their products.

I just got this Folded Space insert for "Star Wars: Outer Rim". I have already glued everything together. I also have the "Unfinished Business" expansion for the game. I've already sleeved the base game with Gamegenic sleeves, and I will be sleeving the expansion at some point. But, I can already see that the slots for some of the smaller decks of cards aren't going to fit. I think the Folded Space insert walls would bow like you were describing. Do you have the "Unfinished Business" expansion as well? Did you get all the cards to fit in the insert if you sleeved everything?

What card sleeves did you use? (brand + thick)

no need to sleeve the cards.