If I understand it right, this question is about behaviour packs in MCBE. As far as I know, those are written in a regular programming language, just using an MCBE specific API. Are those questions on-topic?
This is why this is a difficult question:
- Physical mechanisms in Minecraft are of course on-topic, they are clearly in-game things.
- Redstone is just another mechanism.
- Command blocks used to be heavily integrated into the redstone system and very often there are questions that can have one answer with redstone and one answer with commands. You can basically do everything with commands that can be done in the game regularly. Commands are considered on-topic here.
- Functions are just an accumulation of commands, but they are edited outside of the game itself. They are considered on-topic here.
- Everything else in datapacks is also considered on-topic here, it is heavily integrated with functions and for example often a function needs to be executed every tick, which can be done with function tags or advancements or other datapack related things.
- MCBE's behaviour packs are very similar to datapacks, they are often seen as MCBE's (not quite as powerful) equivalent to MCJava's datapacks. But by now we've gone quite far out of the realm of "do stuff in the game", because this is about programming in a regular, non-Minecraft-specific programming language, outside of the game. But it is still something that is interpreted by the game, just like functions in a datapack are.
- MCJava mod development is considered off-topic here, even though it is very similar to developing behaviour packs. A lot of things can be done with either a mod or a datapack/behaviour pack.
Datapacks and mods already both fall into the area between "gaming" and "programming" and now behaviour packs are in between those two. Do we draw the line before them, making them off-topic here and on-topic on gamedevSE, or after them, making them on-topic here and off-topic (or maybe not) on gamedevSE, or should the line be moved even further, to move all datapack and maybe even command questions to gamedevSE?