I can partially answer your question and suggest something.
Regarding discrepancies, the quality of your GPS signal may affect how accurate the track may be. On my 296, it shows the actual accuracy of the GPS down to the feet on the page that displays the bars for GPS satellites. This may differ then what your transponder transmits to center or approach because the two units may have a different signal strength. Theory anyway for what it’s worth.
Second, regarding the hold entry, check out flightaware.com/live/flight/N992 … 9/tracklog and note the GPS coordinates. You may want to plot the coordinates as that will show you direction of flight.
For my Garmin 296, I have a program called Mapsource where I can download the data from my GPS.
Map derived from Mapsource on a hold I had to do on an Angel flight is displayed below
Hold wasn’t captured on Flight Aware as I was handed off to Little Rock Approach and they marked me as arrived.
flightaware.com/live/flight/NGF4 … /KMBO/KSRC
So I was glad I had the handheld GPS going so I could evaluate the quality of my hold.
Never made it to Searcy as you can see, ended up diverting to Melbourne AR.
100 foot ceilings and 0.25 vis at Searcy and and 0.13 at Little Rock sent all sorts of planes spinning in circles.
Hope this helps.