For Custom Entry Forms, it seems that all our configured subtabs can be arranged in the Form Editor. Then NetSuite arbitrarily appends any subtabs created in code by our suite bundles to the end of the list of subtabs. For example, it looks like Avalara is always the last subtab. It seems that NetSuite is loading the configured form then appending any scripted subtabs. Is there a way to configure the order?

Start learning SDF (Suitecloud Development Framework). I switched over to this instead of bundling and it makes things much easier with more control. Eric Grubaugh has a great course for free. https://hub.salto.io/courses/customization-management-in-netsuite-with-the-suitecloud-development-framework-sdf

Thanks! I'll take a look. I'm looking to manage the order of the subtabs from 3rd party bundles, would this help me with that as well?