Were these posts false
Yes. Yes they are.
The iconic darkroom safelight is usually red or reddish in color. The reason for this is that the black and white photo paper that one is using to print their negative is sensitive to only blue and green wavelengths of light. This means that you can hold one of those unexposed pieces of paper right in front of a red light and it will not be exposed.
However, your Instax film is sensitive to the entire spectrum. Check out the Spectral Sensitivity Curve here. This means that you need to operate in 100% complete and total darkness.
I found a spare cassette. Here's the instax just held out in the open. I've crushed the developer out with my fingers and you can see it bubble up a tad.
Images thumbnailified for viewing. Click to enlarge.
Here's a single pass with a piece of wood to roll it out:
And here's the image on the other side:
As you can see, the whole frame is completely overexposed and where the developer has had a chance to work, the film shows what we would expect (100% white).
So, if you are still seeing this bright red back, it's because you haven't spread the developer around successfully.
If you are getting the developer around, then you need to observe the other side. If it's perfect white, then you have massively overexposed your image and need to alter your process to get less exposure. If it's pitch black, give it more exposure.
Aaaand if it's a perfect red image - you massively overexposed your image with your red LED's :-D.