Does that tool already exist, so do you have a specific TS subset in mind you are aiming for? Or you are simply trying to use fewer complex features?
Our backends are structured on isolated units - what we call "features". Features invoke another features via fully qualified names using a standard Features.send(...). in-process/inter-replica/inter-service and even seperate functions inside the same js files are all invoked likewise.
Only a few specific helper functions for a feature exist for direct invocations.
The complexity of ts2rust tool is thus greatly reduced because of the discipline of the architecture.