I can constantly choose a faction supporter and it never shows that they have been selected and they never show on the stages to assist in roadmap or world stages. I have not noticed any change to indicate if any of their bonuses are being carried over at all. I am also receiving tokens from my faction mates using my toon, but not sure if I am showing up for them.
You have to press the Apply button once you’ve selected the char for the char to be used. Yes, it’s an unnecessary extra step that was added recently.