Would be great to have a form of mapping between Proposals in Defender and the transactions nonces executed through a Gnosis Safe (it could also even work for EOA). The idea is to be able to have a quick way to reference things. Many teams communicates by asking to sign transaction with nonce X.
Also, proposals are defined by a UUID which are pretty good to avoid collisions, but you could also have a local namespace identifier like GRT-1, GRT-2... or FORT-1, FORT-2... depending on the project. See Linear for how they handle issue ids.