The idea has something - and I'm surprised how fast visually scanning for the pattern actually is (once you got the principle).
However, the visual appearance of it right now is daunting. Keep in mind, people are already overwhelmed by a map with hexagons [1] - I think the chances are slim they will want to engage with a complicated grid full of cryptic letters and symbols (unless they already work in IT or public administration).
I think at the very least, you'd have to style it in a way that makes clear that the graphic as a whole is a visual indicator - and that you don't have to make sense of each individual symbol or letter.
I'm just wildly guessing here, but I'd get rid of the letters and only use shapes or symbols to prevent confusion with footnotes. Also you could give the entire thing a recognizable shape, e.g. use concentric circles with segments instead of a grid.
A graphical designer would probably have better ideas how to approach this.
The biggest problem I see is that the way bloom filters work doesn't match the intuition of how to use this signage and misuse could easily lead to confusion and disappointment:
If I'm a traveler scanning for my fingerprint, I'd expect that if I found the fingerprint on some bus or platform then I could trust that this is the way to my destination. However, that's not what bloom filters do: They only guarantee that if you don't see the fingerprint, then that way definitely won't lead to your destination - but they can easily produce false positives, where your fingerprint is present in the signage, but the bus will still be the wrong one.
So imagine you're some traveller, already stressed out and trying to understand an unfamiliar system. You've actually wrapped your head around the system and have finally found your fingerprint - on a bus, which is about to depart, so you jump on it in the last minute with no time to double-check the destinations. You're glad you made it, until you realize that it's in fact the wrong bus, even though the fingerprint said it was the "right" bus. You have never studied CS and have no idea what a bloom filter is, so you're just confused and angry that someone must have put up the wrong sign - and probably not inclined to use the system again for the remainder of the trip.
Edit: Overlooked that you already mentioned the 0.5% false positive rate. I'd agree with the other posters though, that probably no false positives are acceptable here.
However, the visual appearance of it right now is daunting. Keep in mind, people are already overwhelmed by a map with hexagons [1] - I think the chances are slim they will want to engage with a complicated grid full of cryptic letters and symbols (unless they already work in IT or public administration).
I think at the very least, you'd have to style it in a way that makes clear that the graphic as a whole is a visual indicator - and that you don't have to make sense of each individual symbol or letter.
I'm just wildly guessing here, but I'd get rid of the letters and only use shapes or symbols to prevent confusion with footnotes. Also you could give the entire thing a recognizable shape, e.g. use concentric circles with segments instead of a grid.
A graphical designer would probably have better ideas how to approach this.
The biggest problem I see is that the way bloom filters work doesn't match the intuition of how to use this signage and misuse could easily lead to confusion and disappointment:
If I'm a traveler scanning for my fingerprint, I'd expect that if I found the fingerprint on some bus or platform then I could trust that this is the way to my destination. However, that's not what bloom filters do: They only guarantee that if you don't see the fingerprint, then that way definitely won't lead to your destination - but they can easily produce false positives, where your fingerprint is present in the signage, but the bus will still be the wrong one.
So imagine you're some traveller, already stressed out and trying to understand an unfamiliar system. You've actually wrapped your head around the system and have finally found your fingerprint - on a bus, which is about to depart, so you jump on it in the last minute with no time to double-check the destinations. You're glad you made it, until you realize that it's in fact the wrong bus, even though the fingerprint said it was the "right" bus. You have never studied CS and have no idea what a bloom filter is, so you're just confused and angry that someone must have put up the wrong sign - and probably not inclined to use the system again for the remainder of the trip.
Edit: Overlooked that you already mentioned the 0.5% false positive rate. I'd agree with the other posters though, that probably no false positives are acceptable here.
[1] https://www.vrminfo.de/fahrkarten/tarif/tarifwabenplan/