I’m looking at a 14 day Libre board and the antenna is clearly 3 parallel traces that are around the perimeter of the pc board. Looking at your pictures I would say that it appears they are on an inner layer of the board. That dark circle is where they are. And, looking at the backside of the board I see a couple of vias that allow them to connect to that inner layer. The antenna pins of the RF430 are pins 1 and 2. There is a dot above and to the left of the RF430 marking that indicates where pin 1 is. I appreciate you doing this teardown. I’m just now wearing my first Libre 2 sensor. Search the TI web site for RF430FRL152H to find the data sheet on the processor part.

The device in the Kapton tape is a temperature sensor.