To test whether ' is a terminator for an identifier, I tested (list 'a'b) on 42 Schemes.
Returned (a b): Racket, Gauche, MIT, Gambit, Chicken, Scheme48/scsh, Kawa, Chibi, Chez, Vicare, NexJ, STklos, KSi, SigScheme, Scheme 9, BDC, XLisp, Rep, Oaklisp, Spark, Owl Lisp.
Returned (a'b): Bigloo, Guile, SISC, SCM, Shoe, TinyScheme, Dream, Scheme 7, Schemik, Elk, UMB, VX, Sizzle, Inlab.
Syntax error: Ikarus, Mosh, IronScheme, SXI, MScheme.
I suspect that a lot of implementations think it's simplest to just gobble up what they see until they get to an unquestioned delimiter.