Despite the hassle I recommend upgrading the problems to use scaffold.pl -- it's a lot of work but it could be worse -- a lot of the original text and code can be reused. However it would be a substantial project and probably not something you want to do immediately.
scaffold.pl is not (yet) perfect, but it's way better than compoundProblem.pl,
compoundProblem2.pl and compoundProblem5.pl -- all of which I believe are in your 2.13 distro. You might try to switching the problem to use compoundProblem5.pl -- that might have better backward compatibility but would still solve the issue you mention.
I no longer recall whether this issue was known -- compoundProblem evolved over a fairly long time period which was required since in the beginning we really didn't know what features were needed for a problem type like this and it took a lot of experimentation to come up with a generally accepted feature set.
I would say that scaffold.pl is much better, but probably still far from perfect.
Let us know how things work out.