Actually since your rapids seem to be ok you may want to try running the job again with a reduced cutting feed rate (eg feed override at say 70%).
Will do. F360 tooling specs imported from Genmitsu web site for flat end mill I am using sets Cutting Feedrate at 1000 mm/min, I'll set it to 700 and give it a go. Transition Feedrate default on import is 1000mm/min. I am not making consecutive passes, based on F360 pop-up help for this field I don't think this input is a factor in my current dilemma and will leave as-is. Lead-In and -Out Feedrates are set to 800mm/min on import. F360 help states these values should be same (or lower based on job clearance needs) than the Cutting Feedrate. I don't like changing too many parameters at one time without seeing/knowing impact of the previous changes if can be prevented, as these will be close to the new Cutting Feedrate I leave them as they are on import as well.
@PCW : Machine checked for square twice after an adjustment to Y2 (right Y-axis); the second time using the 3-4-5 via mirrored transformation and hypotenuse segment lengths were accurate enough for my purposes. Following your recommendation, I jogged Y alone and then with X to max extents and in between as well as crisscrossing; DRO and manually measured (as accurate as I can get at least) distances and straight paths seem to be jiving up. I am not pushing the drivers or steppers hard like a program would, so my efforts may not substantiate much of anything.
Appreciate the assistance.