At the moment, my suggestion would be to not mess with
`org-emphasis-regexp-components'.
I stayed away from messing with that for the longest time, until a bug got into me to always auto-fill the Org files (as it makes it easier to read them in browser, etc.)
As I started auto-filling, I noticed that stuff like:
=====
Line 1 starts with /three words
italicized/, but the third word ends
up on the 2nd line.
=====
It wasn't always in my control to always begin and end emphasis on the same line, and so resorted to tweaking org-emphasis-regexp-components. Overall it works great, except for cases like these.
Again it's a font-locking bug, and thankfully doesn't impact the empasis detection in exporters.
Would you please look into fixing this?