I mainly use Chord Crush on my Android cellphone (Crosscall Core-X5), via Firefox. Interestingly, the chord playback is reasonable when I use bluetooth earplugs, but is extremely glitchy when I listen over the built-in speakers or headphones plugged in via the mini-jack port.
The glitch I get is a kind of irregular skipping which is very reminiscent of when I’m setting too low a buffer size on my pro audio apps. Maybe you’re being too greedy with buffer size too ? 
Any other audio playback via the browser is unaffected, e.g. youtube video playback is just fine, so this sounds like something that Chord Crush specifically is doing with audio is the culprit.
It’s also worth noting that in general, the app is pretty slow/laggy on this cellphone. It uses a lot of battery, makes the phone heat up a lot, and has a rather unresponsive UI, even on bluetooth earphones where the playback is otherwise reasonable. Perhaps the skipping audio is linked to this high overall resource usage? But if so, it’s unclear why some audio outputs are affected and not others.