So I have a config, but to alter it I need to do carefull editing of the config and double check everything to not break anything.

A tool or interface would be awesome, but with minecraft adding blocks left and right such a tool would need constant updating.
It would be awesome to have the ability to alter flags in game, then later adding submenues for editing the numerical value ones.

Check out scrolling menu signs plugin, it has a Command Book interface
But a simmilar thing might be done with a doublechest interface for more options

I propose:
/ps createfield [-data]

This would create a new field name, linked to the block you are pointing at (as long as both name and block are unique, the optional data flag indicates it should use the data value as well)

Opens an interface that grants access to the different flags.
If there are too many options, create submenus for simmilar items.
Sub menu's for increasing or decreasing numercial numbers (use multiple stacks of 50)

This would allow admins to alter config without the fear of breaking the config and trying to find the typo that did it.

Too much work. Won't fix.