The hearing today covered 'whether the belief was protected' and gave some examples of 'manifestation that might not be allowed even if it was' (although not with Maya's belief).
They gave an example that if an atheist made constant comments to a religous individual about 'seeing fairy unicorns' then that might be harrasment.
It is not controversial (meaning the other side have not claimed) that Maya would, as a general rule, use preferred pronouns. However, she might not if the discussion they were having made it important she drew a distiction between biological male and female (eg about single sex spaces). The Independent article was extremely misleading on this point.
I would presume that if anyone referred to anyone else in the workplace in a consistently derogatory way, then that would be harassment, regardless of whether it was the manifestation of a genuinely held, worthy of respect in a democratic society, belief or not.