You haven't addressed HOW you got these to the wrong size. If you had precut the sheet before mounting then it's your bad. Measure twice cut once.
If you relied on the old printer to print trim marks it may be out of calibration along the feed axis. Easily can be .125" off from that.
Rolands use a Media Calibration (which should be called media feed compensation).. it adjusts the feed advance to fine tune overlap. Even a fly's asshair width per pass can add up real quick.
That can also address your color issue. It will place ink in different screening resulting in color shifts. .
If your rip has media calibration settings on, they can add or subtract from the machines settings. Further, in re-processing I've seen Onyx and Flexi IGNORE those settings intermittently.. just to **** ya off I guess..
As for returns from a trade show use with damage by client.. that's a zone my business would never cover... Here's why:
They used them for the whole show.
They didn't complain at the time of setup. If the signs went INTO the frames, then they were suitable. You can't claim it doesn't fit if you got it into the thing.
The only time I'd accept them back was if they DIDN'T fit the frames right then.
The damage, chunks missing, scratches, etc are clear examples of mishandling and abuse, not defective product. I don't cover goon damage on economy crap.
Sales should recommend they order more durable product, foam core being the least durable single use media, and require that all returns or claims for adjustment are made prior to the trade show, and all frames are supplied to you for fit and finish.
It sounds like they had a bad trade show,, were disorganized and disappointed and turned to you for the recovery.
Now to employee issues.. it's not your concern unless your department's profit/loss is directly tied to your pay or your employment duties on writing. If so, then you need to be able to refuse work that is obviously going to fail, I.e. foam core graphics that large with the intent of being reused, and product going out without laminate.
The way your print shop people are making these is all wrong for anything but one use, and the client should be made aware that those signs sre one time use and can crap out before they get them up.
That is between you and your boss. If it were me sign production and media choices should be a decision made by you if it's your responsibility, not by a litho print shop sales rep. They're likely so inexperienced they don't know what to sell the client.
its only a freaking sign!