I've attached a first macro for thoughts/feedback. If it gets the greenlight I'll run through the steps on the FreeCAD-macros github page.
What does this macro do?
The idea for this macro is to select connected (straight or arc) lines in the sketcher. Select one of the lines and the macro will select lines connected to that line.
How do you use it?
If you execute the macro with no sketch lines selected an options dialogue will come up. You can chose if the lines selected will be normal lines, construction lines or both normal and construction lines.
You also have the option of choosing if the lines selected are lines which might have connectivity error (eg there is a connection to one end and not the other or multiple normal lines). Generally if you are looking for errors to be highlighted then the line type selection would be normal.
The macro will save the parameters when you click ok so you can see them in tools->edit parameters under macro/sketchselector and you don't need to set it up each time and you can set up a hotkey if you would like.
With the options selected - click one sketch line, execute the macro and the connected sketch lines will be selected according to your preferences.