What's the reason not to use Plasma Mobile though? I'd prefer investment of effort into that.
I see the same problems on desktop Plasma, wildly inconsistent padding, UI elements not lining up and bits of the interface crushed and cramped, while 100px below you have gigantic elements.
If you're going to take a swing at doing a FOSS phone right, you really need to avoid the wonky programmer art or you are not going to convince the average user that its any better or more polished than previous failed attempts.