You absolutely can do this (unless I am misunderstanding your point in which case, my apologies). That's why there are dozens of journals in things like lingui

You absolutely can do this (unless I am misunderstanding your point in which case, my apologies). That's why there are dozens of journals in things like linguistic typology and language variation and change. There are linguists whose entire careers have been generating a sort of conceptual mapping between the morphology, syntax and phonology of spoken languages to sign languages so that you can have sensible conversations about the typological relationship between a signed language and a spoken one. See the research of eg Diane Brentari at Chicago or Diane Lillo-Martin at UConn or Wendy Sandler at UT Austin.