SEOs with elements within the module will remain. SEOs with elements outside the module will not, and will need to be recreated on the host file once the module is placed (and, I think, redone with every hotlink update; it is probably best to avoid that road).
If you are trimming a wall to a stair, and there is no way you can make that stair part of the same story and module, you could use for SEOing a dummy copy of that stair placed on a normally invisible SEO layer. The dummy stair could be 'on the floor above' in terms of elevation but belong to the same Archicad story and get published with your module.
