What is 'De Richmond Sigilvm Comvne Libere Scole Bvrgensivm' in English?

Answer 1

This text is not in classical Latin but in medieval or Low Latin, which has a grammar closer to English.

The main word here is sigillum a seal, which you have quoted as sigilum, which may be your error or an error by the original writer. Similarly comune should be commune.

Sigillum commune signifies "the common seal", one in general use by a council, a guild, a school or some other group.

De Richmond simply means "of Richmond", while liber scole burgensium (which should read liberae scholae burgensium) means "of the independent [free] school of the town".

So the whole text, which is very clumsy Latin, means "The seal of the independent school of the town of Richmond".