If your PMS cannot represent a feature as an amenity, the AI Concierge can still match homes by that feature using property tags. It can read property tags as part of what it matches against.
What you can do. Keep the feature as a tag on the relevant listings in your PMS, then ask support to enable tag matching for your site. Once it is enabled, tags sync from your PMS and the Concierge includes them when answering guest queries.
Keep in mind. All property tags become visible to the Concierge, not only the ones you add for matching. Name any internal or operational tags on your listings with that in mind.