I've never seen this happen to me; is there a short sample tex file you can show that reproduces this behavior?
I think this would be completely up to the system admins, so would be different from place to place.
I seem to recall (for the last article I submitted) a caution on the journal's website about using what they called "non-standard" packages. I would send an email to the journal about it. Even if they don't want to accept this particular package, they might have their own way to create the widecheck symbol.