Just a bit of bespoke asset pipeline tech. The .NET process I start at the beginning of the video watches Tiled assets for updates and re-exports them to lua automatically. Then, in love2d I have a similar setup watching loaded assets for changes and hot-reloading them.

With this, I can work on my assets and interact with them in-engine without any reloads needed. Just hit save and it's there!

Blog post with more details: https://huguesross.net/2022/01/love2d-asset-pipeline