I've been trying some different ideas on my own while we're waiting for Necrophyte to return, but as I'm not an expert in the code I'm mostly just guessing. So far no matter how I've swung it, if you make those modifications to lines 822 and 886, the caches will then rebuild but the messages don't import at all, leaving you with a blank site. I may try one other idea, do the import with the 'tag' issue and then see if I can address that another way. Will post any progress I make.