In the config directory there are two files MapWriterBlockColourOverrides.txt and MapWriterBlockColours.txt that contain the id for blocks.
My suggestions are:
1: To replace the ids with the block names, similar to how immibis microblocks for 1.7.10 does it (eg chisel:warningSign:0).
2: To put these two files, including MapWriter.cfg inside their own directory (config/mapwriter) since having multiple files from the same mod in /config feels a bit messy.

i already did the changeover to names in 1.8. :) (also becouse id's can change every time you start the game)

as for the second that is a good idea, will put it on the todo list.

Is it possible to be done for the 1.7.10 version or would it take a lot of work? Considering that most mods have not been ported to 1.8 yet.
If it is not possible for you to implement this, could you please point me to the commit that replaced ids with block names so I could have a reference implementation so I could try to implement it for 1.7.10?

the commit where i (started) changed it is: 91efb00

but if you're going to make a pull request please check the current code becouse if i remember right the first implementation of the names instead of id's gave some bugs