vroom (nl)

As far as I can tell, the noun fruma is the same as the adjective, it's just a substantivised form of it. Kinda like how Dutch has oudere or gevangene. The question is mainly whether this substantivised form can be reconstructed for Proto-Germanic already, or whether it was a purely Old English invention. I think it's the latter.

I'm not sure how to include an intra-OE derivation in the P-Germ. reconstruction page tree; is the sensible thing to omit it?

With descendants we mostly care about the form of the word, and less about the meaning. fruma is without a doubt descended in form from *frumô. So it can be listed, but with a gloss that gives the changed meaning.

Thanks. I also noticed you deleted the category Dutch Terms Borrowed from Old French, but you did not alter my {{bor}} template in singel. Would I be more correct to use the {{bor}} in a dum entry, but to use a more general {{der}} template in the nl entry? Finally, is there a preferred source or normalisation scheme for Middle Dutch spellings?

{{bor|xx}} means that the term was borrowed into language xx. If the word was borrowed into Middle Dutch, then {{bor|dum}} would be ok. But of course it can only be borrowed once in a language's history, so any subsequent languages would use {{der}}.

Yes, there is a normalisation scheme for Middle Dutch, it's at WT:ADUM. In general, you can find a lot of information on practices and rules for individual languages on these "About..." pages.