For past custom type projects, I’ve gone to the trouble of figuring out exactly what character coverage the project will include upfront. Today, I think this is unnecessary. It’s also needlessly complicated for the end client or collaborating agency.
The project might have specific requirements by language or script or intended application (Math typesetting? Wayfinding?) which are necessary to understand to ensure the project has a successful outcome. That is: the font will be useful for its indented use cases.
It’s certianly necessary to know the high-level scriopt support, as part of the goal of the project itself. If you need to support multiple scripts, that is a dramatically different project than a Latin-centric display typeface.
But actually figuring out the character-by-character coverage? I think that is part of the custom nature of the project itself, not a proposal.
As long as everyone agrees on the end goal, this is an implementation detail that can be determined (and probably should be adjusted) during the project.
Until next time,