as the saying goes "can not see it from house", or "when it breaks you keep both pieces". (hope my humor comes across)
ORM has to know the name of the sequence or it can not pre-fetch the sequence, or modify its values
i went and looked to double check ORM does control the naming see
lines 10 -13 and line 96,
Postgresql auto naming for indexes and sequences is tabel_column_type(idx,seq..) the ORM follows a similar logic
changing names outside of the ORM will bugger the app