Personal comments:
C102 shows up in the Flight Planner (I’m also Navigraph user), so it should appear in the FPL on-board. If you’re using the WTG3000, you’ll definitely see it.
Clarification - are you using Auto-Tuning for the ILS frequency? If so, sometimes it’s not working correctly. For ILS, I double-check the frequency inside Little Nav Map. The waypoint information inside the Garmin may also show it, but I tend to manually type it in and make sure the four-letter alpha Ident shows up next to it to validate.