It's essentially DC, so track geometry doesn't matter much, except you want to either keep it short or keep it wide to minimize voltage drop.

You have a trace resistance calculator here: https://www.allaboutcircuits.com/tools/trace-resistance-calculator/

Assuming that main trace is under 15 cm, your resistance should stay below 50 mOhm, so you're losing about 0.5 V at your maximum charging current. If that's not acceptable, make the main track wider or shorten it. These 500 mA feeders look like they're at least 0.5 mm and pretty short, so that should be fine.

At some point, current capacity becomes a concern too, but I don't think you're gonna blow this up with 9 A. Except for that single via on the left, that looks sketchy. You want an array of vias at that current, probably.