Ok, I think I get what you mean.  But I think that you should be asking the gensim people how they find out of word vectors.  Having said that.  I still think that for latin-based languages, it would be almost impossible to find a word that wasn’t composed of any smaller sub-sequences from other words.  And to get these subwords, you use the function get_subwords.  You’ll be able to get a representation of a word that is OOV, but still contains sub-sequences from other words.