I am not familiar with any Donegal records on the IFHF database, but records I've checked for other counties (Dublin & Wicklow) were complete transcriptions of the original parish records. The original records can be very sketchy depending on the timeframe and individual parish. For example my own ancestors married in Wicklow on 1849, and the only details recorded in the register are the date, the names of the bride, groom and witnesses, another marriage record from a parish in North County Dublin around the same time included even more details than a civil cert - including both mother & fathers, addresses for everyone (including witnesses)
I have heard that for some counties the transcripts they hold may not include the full details.
Shane