I use ACTool for running the macros atm.
My bot has the _ABILITY_ to monitor for health on the forge, although I haven't implemented checks for it as of yet. I have a library of functions for use in ACTool that you can use to find CurHP, MaxHP, and a lot of other useful variables, but it's not currently implemented into the bot.
I set a color for each type of event. What the macro CURRENTLY does is it checks those squares for a pixel color. R relates to which of the 3 artisan classes it is (craftsman, scholar, or outfitter), G relates to which ability set, and B relates to which event. If you download the bot code and take a quick look at it, you should be able to see how it works.
I will likely be changing it soon to just be the event identifier, and recover the rest of the information from which recipe it is using. This should let me ALSO have reactions for the new abilities.
The GIMP is the Graphical Image Manipulation Program (G.I.M.P.) - check out
www.gimp.org for windows, unix, linux, and macOS versions. It's similiar in functionality and interface to Adobe Photoshop, if you've ever used that.