There is already the possibility to use a column "stylus" which is very useful.
But maybe the proposition to have another column... hum, whatever, for example SFURPS for Synonym Frequency Use Roughly Percentage by stylus
Well
Not a good idea. The best way for a lexicon is probably to not insert rare synonyms, or, if not, to indicate "(rare)" in the column "word" or "stylus".
"rare" or geographical limit, like for example "(only in California)".
But it should be clear Panlexia is a universal lexicon, not a universal dictionary. Lexicons have some avantages over dictionaries. And not only the fact is far less work to do.
Even if it's possible to use the Panlexia system to make real dictionaries, I think a Pan Lexicon (only the most used synonyms, and about maximum 10 000 concepts, without compting numbers) project should be distinguished from a Pan Dictionary project (a lot of synonyms, and about 100 000 concepts, without compting numbers).