# [SNOBOL4 (CSNOBOL4)], 148 bytes

     S =INPUT
    N S ARB . L ANY('aeiou') . C REM . S :F(O)
     EQ(X) :S(A)
     &LCASE @P C
     &UCASE LEN(P) LEN(1) . C
    A O =O L C
     X =1 - X :(N)
    O OUTPUT =O S
    END

[Try it online!][TIO-kxxmuf41]

[SNOBOL4 (CSNOBOL4)]: http://www.snobol4.org/csnobol4/
[TIO-kxxmuf41]: https://tio.run/##HY7LCsIwEEX3@Yq7sslCoeCqUDDWCEJNatOCLlutWl/x/fr5OnZ15twZLnM7udId@k0Di3CikzxjmkaZDtFDDKkX3Cuq2j08QUGEVE2JFsGYG8GgZnwuEFguSTpxJK3CIEFEkrcSK80T0cJvG5iEQWiom47mCH10CQHXghmYPKMP/mvLlB41TVEuV9V6s613@8Px5M6X6@3@eL7en@8P "SNOBOL4 (CSNOBOL4) – Try It Online"