Sorry for the bad experience with the lack of battles, those are the only ones that have to yet be implemented, the other ones are working.
There are some things that need to be implemented still as the game is still under development, that includes some early balancing.
When it comes to achievements, you don't have to get them all. The game is designed to allow you to access all the content by just playing naturally
If you have any more feedback as you continue playing, or scenes you'd like to see, do let me know. One of the choices in the game was actually suggested by a player on my Discord.