I have looked in many places for such a program, but I have not found anything like it - I have only found configuration editor programs specifically designed for a certain program, where the configuration options and their position within the file is known and hard-coded into the editor. Sure, I could go make my own, but I don't know where to start, and I would have to learn the entire field - just like before I knew how to make my own mods for Minetest without butchering up parts of other peoples' mods, duplicating pieces and stitching them together, and slapping my own label on it. Learning to make my own program for this special task would take much more time, and by the time I "finish" it (if ever) I would abandon my mod projects for other interests, like making other programs for Windows and selling them to make money from Windows "users".
For an example of what the ideal program would look like, refer to these pictures of other specialized configuration editor programs (or built-in GUI configuration editors that are part of the same program):
This is pretty close, as it displays how the entries are loaded procedurally and placed in separate "blocks" and the presence/number of entries can be changed by later developments, but it doesn't show the preferred interface style (it's just a bunch of text boxes, without any buttons or sliders)
This one is a little better regarding the style, but all of the "blocks" are static except for the input control for each option (it would have to be modified if a later development adds new options or changes existing ones)
Surely I'm just using all the wrong search terms and not finding the magic ultimate program that fulfils these needs for developers of different software around the world,... surely I'm just missing the link to some site that links to the homepage for the program that "does all of this plus more you never expected",... I would hate to have to ask someone to divert their time from important development work on the engine just for "please make <insert non-existent wonder-ware here> for me"
If such a program truly does exist, please let me (and the rest of us) officially know about it, so that it can be put to good use in the process of easily editing configuration files for everyones' mods simply by opening a GUI window and clicking on something or maybe typing a little bit of text/numbers into a box; this would be so much easier than the current situation, where you have to scroll to the option in a text window, highlight the text for the previously-configured value, and type out or paste the new value - you can imagine the relative difference in the time consumed when you scroll through a massive config file (like with GregTech) highlighting every other "false" and typing/pasting a "true" or the opposite, as opposed to just clicking a check box or sliding a slider for each entry.
Edit: I can't make my mod load configuration options from a config file until I know what the data structure within the file is supposed to be. If a config file editor program does exist, and I go ahead and make a config file system within my mod before I know about the program, it is highly unlikely that the system would be compatible with the program, or even close to the data structure it expects. Thus, I can not work on moving configuration options to a separate config file, until I know what data structure would be compatible, or just end up making a program and thus defining the data structure itself. This does not mean that I can not continue working on the mod; it just will have to be defined as variables in the lua file that is intended for processing the configuration and telling the other parts of the mod "what to do".