Language A vs B crib?

[Anton]

We then compare the distributions: a reasonable speculation is that the most common words in A are the same plaintext as the most common words in B.

That's not that reasonable if you compare text blocks the subject of which is different - like Herbal A with Recipe B. A pure test would be to compare herbal A with herbal B.

In a highly abbreviated "telegraph-style" text (which the VMS probably is), function words may be absent at all.