wrote...
....
here is another example: -

First Draft.Standard Subjective.Structure Proposal.evd where evd could
be any combination from 2-5 chars long

If it's always on the right end of the string just after the last period,
then all this takes is finding the period.

=LOOKUP(2,1/(LEFT(RIGHT(x,{2;3;4;5;6}),1)="."),RIGHT(x,{1;2;3; 4;5}))