The bottleneck? It's time and money really, or at least for me. I started working on a model last winter in Unreal 4 and made some progress but I ended up working on other projects trying to disprove some false claims made by flat earthers. I made a few videos but I work full time so I can't devote any serious time towards modelling. Others have made maps they claim are correct as far as flight distances and times (adjusting for true air speed) and sun/moon position, but I haven't really looked at them closely. The visual effect of the sun setting and rising is what I was focusing on in my flat earth model. When I have time I will incorporate the different maps into my model and see how they compare to reality.