Perc Data is provided by the same people who provide Schedules Direct. It is the commercial version of Schedules Direct.
Schedules Direct does have Season and Episode data, but the initial version of Perc Data did not. They were planning to add all the data available through Schedules Direct to Perc Data. It sounds like they haven't done that yet.
Perhaps contact Perc Data and put some pressure on? They must be very aware of the issue. But they are all volunteers I believe, with the subscription just covering the source data, so be firm and gentle.
There are some software applications that can enhance EPG data that is sourced in XMLTV format, which is what MC uses for Perc Data I believe. "EPG Collector" is one such product that not only gathers OTA EPG data, but can import XMLTV format data and I think it can enhance that imported data. There are other solutions, but most are old and not being actively developed as far as I know. Google a few.
I'm not sure if there would be issues with the MC setup if your EPG source was Perc Data, but you wanted to enhance that data with Season and Episode metadata before importing into MC. i.e. Run Perc Data collection, enhance using EPG Collector, import data into MC.