You mean like, grass mountains, sand, dirt, town roads, etc?
If it is the case then aim for centrED or centrED+,
If it is walls, items, and such, aim for either centrED, centrED+ or [unfreeze the area to change and do the modifications needed, then [freeze back what you added and unfreezed that stills there.
But either way, all the changes you make to your files, you should do a backup of your original files, just in case you do a mistake or want to go back in time.
And if you wnt your players to see the changes you will need to distribute it to them in order to be able to get the players to see the changes made.
In all: do it only if you are sure about it.