I frequently create content in languages other than English and need to be able to type accented characters. I created these key bindings to get the accents I need using the conventional Mac key combinations. Modify as needed/desired. FWIW, they’re up on github here.

{ "keys": "alt+`,a"], "command": "insert", "args": {"characters": "à"} }, { "keys": "alt+i,a"], "command": "insert", "args": {"characters": "â"} }, { "keys": "alt+e,e"], "command": "insert", "args": {"characters": "é"} }, { "keys": "alt+`,e"], "command": "insert", "args": {"characters": "è"} }, { "keys": "alt+i,e"], "command": "insert", "args": {"characters": "ê"} }, { "keys": "alt+`,e"], "command": "insert", "args": {"characters": "ë"} }, { "keys": "alt+u,i"], "command": "insert", "args": {"characters": "ï"} }, { "keys": "alt+i,i"], "command": "insert", "args": {"characters": "î"} }, { "keys": "alt+i,o"], "command": "insert", "args": {"characters": "ô"} }, { "keys": "alt+`,u"], "command": "insert", "args": {"characters": "ù"} }, { "keys": "alt+i,u"], "command": "insert", "args": {"characters": "û"} }, { "keys": "alt+u,u"], "command": "insert", "args": {"characters": "ü"} }