Ask HN: How do you scale complexity?

I'm working on a tool that will make scheduling meetings with other people super simple.

I have built the tool we have now with a couple angular directives. I do not feel i have a good understanding of angular.

Right now our codebase is pretty bad. No standard way of doing anything, all my angular directives are on different pages, and zero tests client or server side.

I want to switch over to react & redux, but have no way to tell if that is adding unneeded complexity at this stage. Are there any 'hard' and 'fast' rules for deciding when to focus on background engineering tasks and when to keep building the product? I want a workflow that makes sense and is easy to scale, how can I figure out what works for my team and I?