Interesting thread.
OK I’m going completely off the wall here and apologies if I’m a bit tangential.
I’ve used Cubase for years at a professional level and never had any issues with audio rendering, so my thoughts on this matter are ; if you’re not doing anything wrong technically ,which it sounds like you arent, then I would say there might be some professional snobbery ,one-upmanship going on here.
MIght I ask if you’re the youngest ,least experienced member of the group? Quite often people feel they need to put down a new,young less experienced person just to exert their own position and this might be happening here. I’ve seen this happen many times in various scenarios over the years and have on occasion in the past been a victim of it myself.
If its a technical issue then As a test just get the people to null your exported file agains the original they’ve sent and if it nulls then its the same,end of story.
MC