Discogs' API treats companies here like labels and series which have catalog numbers in most releases. If there is no catalog number, there is always just an empty space in the API. But in the HTML page, you see "none" at Labels and Series, an nothing at Companies. This made me letting the script write "none" in all cases. If you want this changed, I can put it on my to do list for the next update. (But don't expect an update soon).
I guess you're talking about the CREDITS; NOTES; IDENTIFIERS; COMPANIES section, because a similar thing is possible at ARTIST NAMES.
Anyway, you can generate extra tag fields at "Companies" and "Barcodes and Identifiers". It's briefly explain in the somewhat incomplete help section at the bottom.
The syntax is:
Extrafields: >TAG FIELD NAME:Discogs Category<
for example:
Extrafields: >MASTERED:Mastered At<>PRESSED:Pressed By<
With "delete extra fields from main section" you can decide if these categories which you already have in extra tag fields are still listed in the "Companies" or "Barcodes and Identifiers" main section.
It's
Combine Credit fields with other fields:
...
- Album Credits Primary Names >no
- Album Credits Name Variations >no
If you combine them with other fields, there will be a headline, if not, there will be not.
Maybe I should have made this clearer.
while "none" in Labels is totally fine as it makes more sense.

