I'll move over to a new thread, as I was adding much information to the stack error post below.
So it appears the installer picked up much of my settings from v25. Infact, it seems to have mimicked my custom directory in v25 (.\pb appended to normal macros directory). That directory got created under v26 but is empty.
C:\SlickEdit2021_b\macros\pb\
If it went that far.. might be nice to copy all the .e files over. I'd love to share one copy for both versions, but it seems the .ex files are versioned.
Look and feel are the same, so I'm confident much of my settings got migrated. I copied my .e files and maybe things will be working well once I compile them.