Ok found the solution myself
In case anyone encounters the same issues as me:
1. Open the MIDI Control Center
2. Click the the sustain port in the main view
3. Change the mode from "Switched control" to "Control" (Enables the half-pedaling function)
4. Invert the values from 127 to 0 as well as 0 to 127 (Needed to do this because the FC3A doesn't have a polarity switch)
5. Go the device settings and change the continuous sustain values to about 16 and 107 (I had to this to correct the min/max values to the full range of 0 to 127; my FC3A only sent 16 to 110 by default, so I need to expand it to its full range)
I wish Arturia would provide presets for different pedals in the MCC. Or at least a support page with tutorials for the most used pedals.