Hi,
I think you want to set the return value to ‘Label’ not the ‘Value’ on the ACF options, and then it will return the label correctly: https://i.imgur.com/0ijg2Jx.png
In the advanced content field, sinply use the {airline} variable, and that will work, it will list all airports, comma separated.
Can you please be more specific about the taxonomy issue? Where exactly does that happen? I am not sure what are you reffering to. Thank you!