I describe my "internal" sensory experience as being similar to proprioception. In the same way you can "feel" where your left hand is relative to the rest of your body, that's how my relates to most objects/spaces.
I was curious: have you noticed any effect on your memory? My autobiographical memory is poor--I tend to remember facts about what I've experienced, but I struggle to recall the experience itself. I can't "mentally time travel" back to the moment and note new details like other people can. I only retain what I noticed then in a disconnected fashion, like remembering an incident in a book or movie.
I've read that people with similar deficiencies (such as SDAM) often also report aphantasia. I've often wondered if the ability to visualize might play a major role in encoding and recalling our experiences.
But I do also know what things look like more or less, and I can imagine layouts of buildings really well. But it registers more in the way you might imagine if you were encountering the object in darkness, or became blind after thoroughly learning the object. I can imagine everything in relationship to each other, sort of feeling over it with my mind. I'm wondering if that's what you're talking about--being able to conceptualize it rather than visualize it.
I did manage to imagine "blue" once during meditation, though, and that was pretty cool. I really saw it when I did--my whole visual field behind my closed eyes seemed sky blue. Normally I just see clouds of purplish dots on a black field, if there's no light shining through my eyelids, and it's been that way all my life. That experience, more than anything, convinced me people who say they "see" stuff in their mind's eye really do see stuff.
I'm definitely going to check out the linked technique. Maybe it's snake oil but doesn't seem likely to hurt to try. That blue experience was pretty compelling.