Text size, I'm afraid not.
The character portrait can be toggled, yes.
It's not a 'cavern', but a 'coven'. You can find it in the Swamplands, to the far left of the main swamp area (where the music and title appear).
You will however need some Flimsy Shears to access this area. You can find a blueprint for Flimsy Shears in the serpentfolk's hideout, where you learned about Sera-Vasir!
Thanks so much for all the kind words and the support! We really hope to make the project feel worth your time and money if you do feel like subscribing to a potential Patreon / Subscribestar, and doing our best to bring as much positive learning from Prowler over to GROVE (whilst still keeping the core GROVE mechanics)
We're going to be investigating this issue as soon as possible, but it may take about a week, as the lead developer is on holiday right now.
We're really sorry that this issue is preventing you from playing, and we'll try and have something for you as soon as we can!
If there is any kind of error message that the game is displaying, please let us know.
Appreciate all the feedback and advice! We're posting this to get people's opinions, so appreciate you giving it!
And yes, I think we agree, we're not going to be making Grove a 1:1 remake. Hopefully our intent is somewhat shown by these images. Some new little tweaks and surprises here and there for people to enjoy, when the time comes!
Due to some of the features and plugins this game uses, mobile emulation has a few issues. We don't officially support it because we don't want to tell people to play a version of the game we know is half-baked.
Some people have still tried, got mixed results by running the game through mobile emulators of RPG Maker. You're free to try yourself if you really want to, but we won't be able to help with any bugs or issues you come across I'm afraid.