OK, I elected to simply use the DFROBOT library, which already has the additional functions included.
I dropped the updated BME680 library (bme680.*) version 3.5.10 Into the DFRobot Library (after installation). I found it necessary to make certain edits to eliminate compilation errors. Ultimately I got it working vis a vis:
22:51:06.437 -> bme begin successful
22:51:07.468 -> Pressure has been calibrated for 96 M above mean sea level.
22:51:08.452 ->
22:51:08.452 -> temperature© :24.66
22:51:08.452 -> pressure(Pa) :100540.00
22:51:08.452 -> seaLevel Press (Pa):101691.94
22:51:08.499 -> humidity(%rh) :39.40
22:51:08.499 -> gas resistance(ohm) :248637.00
22:51:08.499 -> IAQ :0.00
22:51:08.499 -> altitude(m) :79.81
22:51:08.499 -> calibrated altitude(m) :95.66
You can see that all except IAQ are working. That’s likely to be some issue with initialisation/Configuration I guess.There remains a difference of 110 Pa between Sea Level Pressure measured using BME680 and data published by Weather Bureau (1018 hPA). I am guessing that perhaps the reading needs further compensation adjustment for Latitude or temperature. Its a small error however and maybe not worth the effort for my purpose.
There is also an obvious error when it calculates Altitude from Pressure (79.81 M Instead of 96.0 M), possibly caused through the myriad of calculations. Altitude and Calibrated Altitude should be the same value methinks.
Seeed could do worse than simply adopting or recommending this library to users.
I have not attempted to drop the updated BME680 files into the Seed)BME680 library, and do not intend to as I am satisfied with the DFROBOT code.
I will be modifying my own sketch code to use the DFRobot library function calls.
I would not use the BSEC front end in a blind fit, its not at all user friendly, so I suggest that you reconsider redirecting users to the BSEC library.