Its different still. The message ia the same between the sentences but still using different words. Isn't or is not in italian is "Non è". But when you use the other verbs you cant say "Non apre" means "he/she isn't open" its "he/she doesn't open".
Lui non viene in casa mia = He doesnt come in my house. Not he isn't come in my house.
Lui non capisce delle donne = He doesn't understand some women. Not he isnt understand some woman.
Isnt opening is correct and doesn't opening is incorrect. but this is present simple not present progressive
I have no idea how you got to eighty dollars without realizing a problem. And getting rid of ads is all well and good, but really has nothing to do with anything else about the program. Some people seem to have a better experience, but I have always had problems with the speaking exercises. I have turned them off in settings. A computer program is not the ideal place to perfect pronunciation anyway. If pronunciation is your major goal, I suggest you try one of the programs that pairs you with a native speaker for language exchange. If you do choose to continue learning grammar and vocabulary on Duo, I do suggest you still read all the Italian out loud. Consistently practicing getting your mouth around the language is important. But a computer is never going to judge your pronunciation well.
A contraction isn't really grammar at all, let alone bad grammar. In formal writing, contractions should be limited as they are a less formal element. But Duo's standard is essential the spoken language. They are teaching you conversational Italian, not how to write formal documents in Italian. But every answer for each exercise has to be specifically included in a rather complex, comma delimited database. Generally something like this is just an oversight.