Firstly, if you are using bluetooth headphones, please be aware that bluetooth, the technology itself, adds a lot of latency. This isn’t an issue with Koala, it’s an issue with Bluetooth. Open any other app on your phone, you will see the same problem.
Secondly, android sucks at latency. It’s a well known fact, it’s actually a standing joke. Just check these graphs. Bottom line is, Android phone manufacturers don’t care about selling you devices with low latency audio, all they care about is GB of RAM and HD screens, not about the actual experience (the one exception is the google pixel range) Huaweis are the worst in this list (160ms!!!).
There is nothing I can do beyond building a time machine, going into the future where civilization has cracked proper low-latency headphones, and bringing them back for you. Again, my knowledge of building time-machines is somewhat limited, so by the time I’ll have finished it, low latency bluetooth will have arrived anyway, so I’m not going to bother trying.