On the logger: one thing that paid off for us is keeping the last ~200 lines in a ring buffer in memory and attaching them automatically to any bug report or crash, along with a small dump of game state. Most player bug reports are one sentence, and those 200 lines are usually where the actual answer is.

On the license: AGPL is a fair choice for your own game, but for a template it'll scare off a lot of people, since anything built from it inherits AGPL. If you want others to start projects from it, MIT/Apache for the template (or dual licensing) is more common in the Godot world.