wow oh wow, it took me a few days to parse your notes. Let me try responding to them in order...
Though I have to remind you that this game is not a 1-1 copy of real life, and many aspects are different for the sake of escaping from the hustle and bustle of everyday life... use your imagination!
are the songs you use original? The ones with singing. I mean, I'm pretty sure they are because I think it's the same voice actress you use for Zinnia, but I've always wondered.
None of the songs in the game are original (otherwise I'd have a big hole in my wallet). I source them from https://dova-s.jp/ . I hired 2 voice actresses with very similar voices to the singers for the vocal songs, https://x.com/Mochitukisiro & https://x.com/sato_sioo
My first question is in regards to what you refer to as Zinnia's hometown. She says it's Montreal, but then this is immediately contradicted by the fact that Zinnia is original from a rural town in Northern Ontario.
There's the fact that one can feel that they have multiple hometowns, especially if they feel connected to it. Since Montreal was the place where Zinnia first began her adventure, she feels Montreal is her new hometown.
Next, I just want to point out that Zinnia calling all of this an "opportunity" she was "given" is just the most incorrect thing ever.
Yup, she is an naive and unempathetic brat that only has her own interests in mind. I was like that too once! But she does change for the better over the course of her adventure.
how old is Zinnia supposed to be exactly?
The characters don't have defined ages for the sake of mankind. If you are serious about it, try taking a good look at Zinnia, and use her height, behavior, and appearance (maybe not a good idea given the artstyle) to get a good sense of how old she is. Remember that this is not a 1-for-1 copy of real life, and the characters could age differently!

Onto the adventure portion.
The next note is actually in regards to time, specifically the time of the train ride from Montreal to Ottawa. In game, Zinnia says it's been 3 and a half hours since she left Montreal. However, I've done this train ride a few times and it doesn't take that long to go from Gare Centrale to Ottawa Station unless there are delays
You are right that the train ride only takes around 2 hours-ish, and I made Zinnia incorporate her time at the station and getting there into to 3-and a half hours. Perhaps I should make it more obvious.
What museum in Gatineau did she want to go to?
The museum I am referring to (which is no longer free of charge unfortunately) is the Bytown Museum, which is back in Ottawa. Zinnia goes to Gatineau after her futile attempt at admission. https://ottawatourism.ca/en/see-and-do/bytown-museum
So you say that the cafe is located on "university grounds" and later say it's right beside dorms. This would likely be the University of Toronto. However, Zinnia goes to Dupont Station.
In Ikimashou, Casa Loma and the surrounding George Brown College are the sites of an imaginary school. Dupont station is nearby, no?
ZINNIA, WHY ARE YOU GOING SO FAR AHEAD THAT YOU CAN'T HEAR WHAT THE PERSON GUIDING YOU IS SAYING?!
She is too overconfident
Also, really? Jamaican patties?
Beavertails are overrated and expensive, Jamaican Patties are everywhere and cheap and filling, come figte me
My next note is in regards to what is likely a typing error. Zinnia plans to go to Toronto Island using the ferry...
She does go to the airport, that kinda counts as Toronto Islands??
Alrighty, now time for my last note: when Zinnia mentions that her adopted mother had to pay tuition for her.
I'm not sure how to respond to this other than, "use your imagination", maybe in Ikimashou all schooling requires tuition or something else. It's one of those things not to get too ingrained about.
I have corrected the writing errors from many of your notes, thanks again for the feedback, and please look forward to the main release of v7.05 in probably around a year or so!! Also, have you read further on into the game? There are 2 specific scenes with Claire that I think you should really see, now that you've mentioned stuff about the songs in the game.