Who'd a thunk it? Seems to have worked. I didn't disable the Type Core, but I deleted all non-system Helvetica sets from Suitcase. Did the safe boot, which as we've already seen, works in the short term. The litmus test was to do a regular restart next, because that's when the problem returned. In fact, before restarting I opened up a few InDesign files to make sure all my needed fonts were loading including a file that needed Helvetica Nue and everything was ok. After the restart, the iCloud page text was as it should be in Safari (same as in Aurora and Chrome). Hopefully, I'll have the same result with the MBP.

Thanks for the guidance.