To elaborate:

I need to input pairs of Time and Temperature (we're following a set temperature curve).
There's an optional amount of lines. Thus after each line, I either add another one or I save and return.

I'm thinking the runtimemenus might provide these additional "lines" I'm talking about. But, at the moment, I'm not seeing how I can get around to getting two modifiable values on one line:

T[50] - [60] mins
T[60] - [15] mins
add
save and return

Suggestions?

You can make your own renderer quite easily, essentially you just rename the renderer that tcMenu put in place for you and change the drawing as you need it. This isn't built into the standard renderer at the moment.

Take a look at https://www.thecoderscorner.com/products/arduino-libraries/tc-menu/customise-menu-input-display-plugin/

Thanks

By the way, to make this easier, I'm going to add an example in an upcoming version with a customized renderer.

That would be great. An example makes all the difference.
I find it somewhat difficult navigating the libraries.