Hi,
Airtable has formula operator exactly for multiple choice:
SWITCH({Name},
'x','email x',
'y','email y',
'default value(optional)')
but in general, hardcoding such tables in formulas is a bad practice. as soon as you start using it in 2 or more places, and team list will change, you will find it harder and harder to maintain.
it's pure Airtable basics - when you store list of team members as a single source of truth, when you need email and other info, you add field, linked to 'Team list' table and get all additional data via lookups.