I was thinking of OTR coats with decorative buttons and OTR shirts. I was not thinking bespoke because there would be no need to shorten a bespoke sleeve.
As for the process, I'm sure it it is labor intensive, but the difficulty of the task aside, I still don't know how shortening sleeves would change the rest of a garment. The OP wanted to know if the sleeves could be shortened and the rest left the same.
Again, It is not my intention to be rude, but I can't think of any possible way shortening a sleeve would alter any part of a garment except said sleeve.