Denote experimental lujvo and fu'ivla as such

[Wuzzy2]

Experimental gismu and cmavo are clearly denoted as such, so there’s no reason why experimental lujvo and fu'ivla aren’t.
Maybe this could be automated?

A lujvo is called “experimental” if at least one of its rafsi is derived from an experimental gismu or cmavo.
A fu'ivla is called “experimental” if it is in stage 3 and the used “topic rafsi” is derived from an experimental gismu or cmavo.

[lagleki]

For stage 3 fu'ivla there must be first implemented an agorithm for detecting them.

[Wuzzy2]

AFAIK vlatai is capable in distinguishing stage 3 from stage 4.