This is solely my opinion and not a legal advise.
(1) If you forgot to mention your previous visa refusals or declare criminal cases you have had in your past, please don’t panick. Your approach should be; okay I have a problem, so what can I do to fix this problem? what is the solution?
quick tip: beginning tomorrow, check your spam mail or inbox at least once in the morning and once at night. Also, try linking your application to your GC key account at least once every day. This is a better strategy than being fearful or having sleepless nights.
Once you get your application number or when you are able to successfully link your application online, please quickly send them a webform to fix the mistakes. If possible, attach a letter of explanation detailing what happened and how you have fixed it.
The earlier you fix the mistake, the better.
Think of it this way, you declared your visa refusals when you were applying for your PGWP, so why will you hide it now? It is clearly a mistake and explaining this and making the right correction ON TIME makes absolute sense.
(2) If you forgot to include some documents or forgot to include LOE explaining why you could not get those documents, please quickly send a webform once you have your application number.
Panicking or worrying over things you have no control over at the moment is a waste of energy
and time and will drain you from finding the solution.
Also, let every applicant (including myself) pray for Favour or luck. The visa officer handling each and everyone’s application ultimately determines the outcome.
Finally, do not let anyone intimidate you! Stay positive and we will all come back here in 2, 3 or 4 months time celebrating our COPR.