I think with the confirmation a few days ago from Fabrizio Romano's tweet, it is quite certain that Guirassy will become a Dortmund player but it seems that it is still being postponed due to medical test reasons. I don't know if something like this will happen and if Dortmund lowers their fees then Stuttgart will inevitably have to accept that.
The reason is that the medical test is one of the determinants for players to be able to join their new club and of course Dortmund knows the risks even though they are willing to accept Guirassy and pay him that amount of money. Now the decision lies with Stuttgart and it feels like this is a win win solution for both teams. Guirassy could still perform well and Dortmund certainly wants that in the future even if an incident like this occurs.
Signing an injured player is not part of any legal and acceptable deal that is why medical examinations are being taken seriously in order to ascertain the well being of the player. If Guirassy is a having a very big injury that will cost Dortmund more most to maintain and keep him, I think they will just have to reject this agreement and no go on with it. It is fine if the deal has already been agreed on and signed before they find out about it, but if it wasn’t, then they should just reject it because it might cause them more harm than good if they want it keep him and the injury is severe.
While he was still playing he received a lot of instructions from Pep Guardiola, he should be able to absorb knowledge which he could then develop himself. There are many things he can learn while still being a player. We have to be a little patient to wait for how he will perform with Bayern Munich next season. Because right now we haven't seen what he will implement, so we have to be patient at least until they play their first match.
Kompany must have learnt a lot from Pep Guardiola and that was why Pep always showed praises on him. They are some things yet unknown by Kompany that Pep can see in him, that could be amongst reasons why he’s like by Pep as a manager and not only as a player. Like you said, he should be given some time to prove himself of what he can do for Bayern Munich, because we can’t just come to a final decision that he is bad and he won’t make a good fortune of the Bayern Munich team.