There are so many patristic works that it's probably impractical for Accordance to offer modules for them all. You either have to work with paper or find your own electronic text. In general, for works in the Patrologia latina, you can download plain text or XML from Corpus corporum. I don't know of anything comparable for Greek. If you have access to the TLG and it contains the work of interest, Accordance can convert the TLG file to a user module.
In the case of Origen's commentary on Romans, the CPG (Clavis patrum graecorum) tells us at no. 1457 that we only have fragments of the original Greek: the rest survives only in a Latin translation by Rufinus. The Latin and some of the fragments can be found in PG 14, 833–1292. I don't think you'll find an electronic text. More recently, Sources Chretiennes published a new edition in vols. 532, 539, 543, and 555.