Okay, so I’ve been working on my map, and I got the thought of adding in area portals. I added in one, it leaked, I fixed the leak, it found another one. It finds a leak through every motherfucking hole (even if one doesn’t exist!). Are there any tutorials on area portals for complex (big) maps? Or am I supposed to use hint texture on big maps?

Areaportals must close off a specific area of a map completely. If you can find a way from one side of the areaportal to the other without going straight through it, it’s considered a leak. I suggest you read this.

Do transparent textures count as a leak?

If light can cast through them, yes.

So what do I do with that transparent grate texture that the area portal keeps going inside it and finding itself on the other side?

I’m not quite sure what you mean. Could you post a screenshot of where you’re trying to implement the areaportal?

Place an areaportal across it, or an areaportal window if that’s more suitable.