At last they are fixing the misunderstanding. Now the author doesn't need to use fainting as their main narrative tool
The issue is that the fainting has left the MC with no character agency. You can have anything as a crucial part of the story, but the readers should still feel like the characters' decisions have an impact of the plot. I have read many stories where the MC is extremely ill, but there is more plot going on that him fainting. Remember, a single part or element of the plot shouldn't consume the entire plot.
This is genuinely one of the best BL stories I have read in a long time. Every character shines on its own, though some do it more than others. The funny moments are hilarious and the world building is simple but highly efficient. The subplot of the King and the Duke is also one of the best subplots I have seen