You might be interested in XIV-Hunt software, it does what you’re looking for, and more. It’s free, it’s new, updated often.

You can sort Hunt by expansion (ARR, HW, SB) and by Rank (S, A, B), as well as any FATES and any Special FATES (Odin, Behemoth, Regina Coeurl, Ixion).
You can attach a different alert sound to any of them.
And the most important feature, it uploads automatically to their server anything a client found, and then spread it to everyone using their client, and report it into your console log according to your filters, with a clickable map flag.

For the alert sound, I took windows text to speech voice, and recorded it while making it say for example: “Attention, attention, a Rank S target has been discovered.”

You won’t miss any Rank S any more, enough players are using the software so that every time someone found one, or even ran by one by random chance, everyone else is alerted immediately.

Another example, for weekly Elite ARR B rank, I just go to the zone, and only there I set the software to alert me for ARR B rank, and I start to explore the map without paying attention, and very soon the software will tell me where it found a B target in this zone.

So, if it is what you’re looking for, get the client here:

https://xivhunt.net/

Wow, that’s extreme.

Then yeah, you can only use it for B ranks in your case.