CrusaderDeleters

Alright. Stop insulting people indirectly.
I'm pretty sure adding a sword entity to the game is NOT a feature of the game. If it is, where can I find it without mods / third party editors?

It was designed spawn any entities, because it's faster than making new blocks to allow to spawn a Zombie, then a Skellie, then a Spider, then a cave spider, etc. This works for Mob Eggs too, you can "spawn swords", but the swords disappear before you see them. It's easier to make one egg, that can spawn any of the current entity list, than to make 20 eggs individually. Same with the Spawners. Better to make one Spawner, that can spawn any of the current entity list, than to make ~6 spawners individually.

These entities you are trying to add (Like swords) were never intended to be implemented into the game, so mojang never needed to add boundaries for these to be spawned.

He's using a mod to make the other entities spawn.
The mod that alters the Spawners to be configured and spawn those entities should make the requirements themselves. Mojang shouldn't take their jolly own time to patch something for mods, when the mods should do so themselves.

Mojang should make a compact self-sustaining dust that could continuously power itself, or be able to easily hide & attach to blocks like these, and keep them powered.

They don't follow this path because they think it's a completely full block. Same thing happens to Fences.

I think that the actual Mod you are using should be making the spawn requirements.