Tri-Flow is arguably not an ideal cutting fluid. It's possible the threads may have been damaged, especially if the taps were dull and/or not cleared of debris. In the past, some manufacturers, e.g. Campagnolo, offered slightly oversize cups that would help in this situation, but they are quite rare now. I agree that if you can seat the cups solidly you shouldn't have a problem. Otherwise, you may need to look at a threadless cartridge or reaming and tapping the shell for Italian threads.