Premature of me. I figured out how to modify the formula for additional columns.

In case someone else comes across this thread, here's how:

{=IFERROR(INDEX($E$1:$O$1,MIN(IF(ISNUMBER(SEARCH(IF($E$2:$O$135="","||",$E$1:$O$135),A2)),COLUMN($E$1:$O$1)-COLUMN($E$1)+1,COUNTA($E$1:$O$1)+1))),"Uncategorized")}
In the formula above, you can change the 135 part to whatever range you'd like:

$E$2:$O$135="","||",$E$1:$O$135
You will also need to change $O$1 part to the range of your headings:
$E$1:$O$1
Thanks again NBVC!