You can't. If there is a question, asking the author is the best way to arrive at a "term" for its state. Using your own good judgement, researching usage in the wild, reading the code, etc, etc, is your best defense.
There is nothing stopping an author from treating a declared "stable," "production ready" module as alpha. It's not particularly cool but it's a FOSS world and I'd rather have everyone be free to be jerks than attempt to institute the jerk police.
Conversely it does seem that authors tend to exaggerate the alpha/beta states of things to cover their own rears and not come off as aforementioned jerks. Apparently NO WARRANTY, AT YOUR OWN RISK, etc, etc isn't enough. It's almost like repeating things in all caps makes one quickly tune things out.