This seems to be speed related, I just repeated my test with the GA aircraft with taxi speed set to 10kts and they behaved more or less as they should with only a couple of minor deviations but they still tend to cut the corners. Also found a bug in the performancedb, <type>light</type> should be <type>light_aircraft</type>
It's mostly all left turns on the ground following the groundnet, the longer wide turns seem to be ok. The first half of the first video shows what happens if the AI turn left onto the main taxiway after pushback and the second half shows a right turn onto the taxiway. The right turn operates correctly but the left turn tries to turn right before turning left, this usually results in the AI detaching itself from the groundnet and either attaching to the groundnet elsewhere or taxiing directly to...
AI Traffic Left Turn Bug