first, there are a lot of old/literary conjugations of the auxiliary verbs. it's a lot of computation for words rarely used in modern french. but the problem is really that some words are wrong. été is the past participle of être alright, but it's also the noun summer, so you probably don't want it as a stopword. été as past participle is invariable so the words étée and étées do not exist and étés exists only as the plural of summer. it's almost the same for the present participle étant: invariable but used as an adjective and a noun in philosophy, so either the word does not exist or you don't want to delete it. as and fut are nouns too. edit: forgot some other polysemic entries: suis, est, sommes and avions