Well, I don't know how describe separately(I'm mean separately tickets) this feature suggestion, because these things links with each others in some way. So I'll make in this way.
This feature might be a very challenged to make and surely this not to do for next version of MCreator(1.9.1).
I mean a block's properties, procedure blocks/triggers or new object(whatever) that affect on area counted in world's chunks.
Most common known example is a chunk loader - block whose placed cause dynamically loading world's chunks, makes them active, even if player isn't around. To cease this effect, player must just break up that block.
So I would like you to implement such area function that affect on choosen by user area. There user will could choose 1x1, 3x3, 5x5 etc of chunks area to affect on it on desired effect. As for height, user will could choose just number of blocks as up and down.
As for effects that be affected on selected chunks area there is:
1. Chunk Loading - works as I'd mentioned above. Very useful for user build machines or farms(crops and animals)
2 Preventing mob spawning, where mobs(especially hostile monsters) can't does spawn naturally, even in pick darkness. This is don't apply to mob spawners, or mob spwned by player from eggs. Very usefull and comfortable for build safe homes and bases.
3. Increase mob spawn and eventually decrease distance of mob spawn from player.
4. Other effects that can be defined by users due to proper procedure/trigger blocks. For example applying potion choosen effect on player/mob whose is in this area.
Issue comments
Minecraft has mechanism to prevent actions in unloaded chunks to prevent DoS-ing servers with mods that would allow this and placing blocks might be prevented too. I will see if we can add procedure block to update chunk but might not be able to for all cases for the reason above.
We will consider adding some of these procedure blocks, but for actual actions in the area, this is already possible with some basic mathematics and loops in procedures.
Check this ticket from yesterday: https://mcreator.net/tracker/issue/53001