It doesn’t really matter if anyone else’s priest accepted an online marriage preparation course. It only matters what your pastor will accept.
Talk to your pastor. If you and your fiancé have a need to work something out as it pertains to marriage preparation, I’m sure the pastor will work with you.
In my case, my husband and I lived in different states. In his state we could do a one day marriage prep whereas in my location it was in meetings over a period of time. So we did the prep course in his state, and my parish (where we got married) accepted the certificate from that course.
Bottom line: You need to ask your own pastor for guidance.