I've always thought it was pronounced TRI-fo, like "trifle" but with -o at the end. A very tight long 'i' sound (not the extended long 'i' of TRY).
But all three speakers on https://www.howtopronounce.com/trypho/ pronounce it TREE-fo. However that is a user-contribution site, so I'm not considering any of them to be authoritative. I can't find any other written documentation of how it's supposed to be pronounced.