The scripts just display the values received. They recalculate if another unit is requested than the one in the upload-file
WU => upload file 1010.84 hPa / 29.85 inHg => displayed correctly on the dashboard for hPa and inHg
Weewx => upload file [10] => 29.89 inHg => displayed correctly on the dashboard for hPa and inHg
Maybe you are uploading station-pressure to the dashboard and the correct sea-level pressure to WU?
I see there is another discussion about this at Weewx and Acurite 02032C Barometer Reading
Wim