no option to home just Y axis on gantry with 2 Y motors

Thinking out loud:

What if I made two home buttons - one for Y1 and one for Y2 and then called them out in the vcp HAL file like this?

and

Or is that just wishful thinking?

I think the halui.joint.N.home pins for y1 and y2 should be connected to the same button so that it's not possible to activate them independently. I had tested it in a simulation and it was working there. I didn't look through your configuration files to see if I could find your error.

Would it help to add a kinstype=BOTH callout to my INI file?  I'm assuming that's safe to do since my config has it so that nothing actually moves when it homes.

Is the error and failure to start LinuxCNC because of the homing thing or something about the formatting of the halcmd it's trying to run for gladevcp?

I just noticed I had the "HALUI = halui" line in my INI file's [HAL] section commented out.  Should probably uncomment that since the VCP HAL file is calling out halui pins.  

I uncommented the "HALUI = halui" line in the INI file's [HAL] section.  That had no effect on the error message, but was something that needed to be done anyway.

Then, I added "kinstype=BOTH" to the end of the "KINEMATICS = trivkins coordinates=XYZY" line in the [KINS] section.  That got rid of the part of the error message that said:

But the other parts of the error were still there (the warning about forward kinematics handling duplicate coordinate letters and the GladeVCP command error).  Is there something wrong with the line that calls out GladeVCP in the INI file's [DISPLAY] section?  It currently says:

I might be wrong and am too lazy to check the docs but I have a feeling shared joints must start with -1 in the ini file and you have used -2. Try changing that