regsvr32 syswow64\oleaut32.dll. I think I originally had the same error as you.
Yep, this did the trick:
x:\windows\syswow64\regsvr32.exe /s x:\windows\syswow64\oleaut32.dll
I believe I had tried that before, but that must have been back when I had the languages mixed up.
(BTW: So XY could have registered this itself, like Excel did?)
So now I have my favorite file explorer working. It's actually an old (free giveaway) version: 11.90. Normally, free versions don't have the nice "portable file associations" feature, but 11.90free has it. Launching documents from XY always starts the correct program, associating them is very easy from an ini file. Very easy to configure, works on any OS (incl. PE), I use it on all systems. Great on w10 as well (which keeps "stealing" assocs).
Just wanted to share why I like XY so much. Of course, the author could/ should have made a 64bit version by now...
With XY as my file explorer, TCCLE as command line, and Autohotkey as PE shell (!), things are starting to look pretty good. (Ask me about ahk as a PE shell...), Oh, and of course WinNTSetup for OS installs, and TSE as text editor. Etc., etc.