In the latest interview of Casimero, it was said that he is already 80% prepared so far, therefore I expect that he has no health problem anymore and all he is doing now is just training hard to maintain his good stamina and improve his skills as a boxer.
That's good! 80% is already a lot specially in his body condition right now and about his health, I also don't think that there's something that we should worry about because his team have already covered that area well enough and must not forget that he have the best conditioning coach.
Few days ago, I saw a video about Casimero doing some trainings and seems that he's already fit enough and there's really no sign that he isn't already well prepared. Here's the vid, https://www.youtube.com/watch?v=Q6-HKZmwYag