I find it quite remarkable how quickly some are to poo poo genuine facts in preference to hearsay comments and half truths.
It is inconceivable that Tasmin mixed up the apartments. Apartment 5a is unique in that it is the end apartment with its own private entrance right onto the main road. I have no doubt Tasmin knew what she was talking about, she lived there. Tasmin was a superb witness and for that reason it was expected that attempts would be made to discredit her. That's how the myth creators work.
As for the connection between the death of the grandfather and Eddie's alerts are concerned there is every reason to believe that there is such a connection if Eddie was as good as Martin Grime claimed. There is certainly as much reason to believe that there is a connection to Tasmin's grandfather as there is to the theory that Madeleine died in the apartment. At least we know for sure the grandfather died and there is every reason to suspect that at least some of his clothing was brought back to the apartment by his wife.
Was his remains brought back to the apartment and waked?