When I used Ren'py for my Visual Novel needs, I never went all-out on transitions. I did mostly fade and dissolve for everything from expression changes to BG and CG changes. This worked well, at least for me. I wasn't sure how to implement these transitions and typewriter type effect in Godot.
Then I found out everything the AnimationPlayer node can do. Transitions, text effects, and more can be implemented with just this one node. It interacts with other nodes and makes key frames from these other nodes' properties.
This. Is. PERFECT!!! This was what I wanted!! Since it's easy to edit what the dialog boxes will look like, I might keep using Godot as my go-to engine for all my projects now! As long as people still support the engine, easy open source game development is totally possible!
Join me this weekend, though, on Twitch, as I try to figure out making online multiplayer modes.