Prototype one representative scene in Flax Engine with your target visual style, input, lighting, and a basic gameplay loop. Package it for the intended platform and test frame time and loading on real hardware. Then make a small source-control merge to see how assets and scene files collaborate.
Review licensing and platform support for your actual release plan. Keep a reproducible build and source assets. An impressive editor demo is less useful than a reliable shipped build that the team can maintain.
Akousa