Eventually, we'll see Superman make his final Filmation appearance, and several years back, Wonder Woman made her animated debut. Both episodes, coupled with Batman's 2 appearances on CBS' New Scooby-Doo Movies, ultimately led to Super Friends the next year, with Hanna-Barbera getting the license, as Filmation's license with DC was expiring.
But that wasn't all.
The Lone Ranger made his Filmation debut a week prior to "Cindy's Super Friend". Seems Bobby Brady (Mike Lookinland) was a big fan of the Lone Ranger reruns, and there supposedly was still existing a Lone Ranger Fan Club. Next thing you know, thanks to a magical contrivance from Marlon (Larry Storch), the Ranger (John Erwin) shows up, with Tonto alongside. Silver winds up in the Brady treehouse, while a pair of thieves decide to pose as the Ranger & Tonto.
It certainly sounds like Jay Silverheels had reprised as Tonto. Silverheels also guest starred on The Brady Bunch, which might've been around the same time. Erwin used the same heroic voice for Dick Tracy a year earlier (Archie's TV Funnies), and, of course, would return to that timbre 11 years later as He-Man. One wonders what the studio was thinking when they signed William Conrad to voice the Ranger in the 1980 series.......