Hello @v_v_ramarao ,
We are looking into the temperature calibration of the on-board baro. PX4 has a calibration procedure for sensors, including barometer : https://docs.px4.io/main/en/advanced_config/sensor_thermal_calibration.html . You are welcome to try this on your own if you are able to.
Additionally, we will work on providing instructions for enabling external barometer. I see that you want to try BMP280, which is supported by PX4, so we will try it, as well as external ICP-101111, which is very similar to what is used on VOXL2 / mini right now.
Regarding the mechanical mounting concerns on J6, J7, I will pass your comments to our team.
Thanks for your patience, I will get back to you early next week.
Alex