You found this FAQ, so that is a good start. 
Aside from the implied connections elsewhere in this FAQ, try these direct places:
Twitter: Search for "#Intellivision"
Facebook: Intellivision Retro Gamers www.facebook.com/groups/1631170557158100/
Discord: Intellivision Fan Group disboard.org/server/682739902504632320
Atari Age web forum for Intellivision: atariage.com/forums/forum/125-intellivision-aquarius/
Intellivision online web forum: intellivisiononline.forumotion.com/