Ok, so sounds like what you said and what the link you shared shared said is what I did. So that means the Saber and the mirage are using PBR in v2.2+. So all things being equal, I could probably help you fix your issue. As far as know the SDK is closed and so there's no official guide to painting. However I used War Thunders SDK for PBR. To me, it sounds like a combo of issues. If you've done these than forgive my ignorance.
1. Remove the AO (Shadow) layer from the Albedo texture (old diffuse).
2. You need to ensure the colors you are using Sheree to the standard color palette which we're going to assume that they do, and ensure that their brightness is set for the type of material each part of you r paint is. So blue, would be blue paint over aluminum surface. Consult the War Thunder SDK, but there is a brightness value threshold that will correspond to "paint".
3. Next you need to edit the RGB channels appropriately for the type of surface appearance you want. That guide you posted is what I did, although I didn't use that guide!