Revenge of the Mummy has been one hell of a mess for quite some time - everything from the animatronics (boy, Imhotep I hasn't been anything but cringe-worthy in nearly a decade), the lighting (turntable scene has been astonishingly illuminated for so long), to the projections (Scarab scene is WAY too bright, I can never make out what I'm supposed to be seeing in the turntable, etc.).
It's a mess of a ride. It was built on the cheap in an era where the parks were desperate for a quick fix that included a coaster track to advertise. I'm honestly not sure why everyone loves it so much... typically theme park fans usually have higher standards.
To be clear - HUGE fan of Universal, including The Mummy property. But I don't make excuses for them, and while this ride is "fun," it is not by any means "good" as a themed experience, even when running at 100%. It needs a huge overhaul and reimagining to be brought up to the standards with the rest of the park (as did Jimmy Neutron's Nicktoon Blast, another ride built on the cheap. Shrek would ideally also be up for some help.)
As for your Transformers problems... sounds isolated to the vehicle. The effects that usually go out are the smoke screen and the heat, which I understand have had some issues recently.
Forbidden Journey is miles ahead of Revenge of the Mummy but it's still overall a mess of a ride in terms of narrative & show elements... the new profile has really messed with the ability to see backstage elements creeping into your line of sight. I know it's impossible to do anything about it, but ideally they'd go back and give this a thorough reimagining, too, now that they have the money to spend.