Trigger validation error upon ajax result?

Question

I'm trying to figure out a way to trigger spry validation
error to prevent submit when the ajax lookup (my custom built, not
spry related) returns a flag telling userid or email already exists
in the database. If I add onSubmit even to the form tag, it'd
override spry on submit event listener. My only option is to try to
tap into spry validation to trigger its own error instead. There's
a spry custom validation that can call a js function but it expects
a true/false upfront whereas the ajax call requires some wait time
and calls another process handler to handle the returned
result.

Answer 1

I am pretty certain that the local proxy (which was in place) is being bypassed for all calls and the box has direct unfiltered access to the internet.
This is also clarified as in any browser I can go to any site http/https, regardless of if 'automatic detect proxy settings' field is turned on or off. I can also get to certain websites on this network that would normally be blocked which also makes
me think that the proxy is off.
Further to this, the App Store applications are actually available to view/search in SharePoint. The error above though only occurs only an App has been download and is about to be added as a web part on a page (after the prompt to Trust
the app has been selected). This to me indicates that it is finding the store ok but having certificate problems.
The first error that I get in the log appears the most suspicious but no idea what could cause this:
RevocationStatusUnknown: The revocation
function was unable to check revocation for the certificate. 
OfflineRevocation: The revocation
function was unable to check revocation because the revocation server was offline
Is the revocation server a local service? If this is a proxy problem what Application/Service is calling this check? Does this access the revocation service via a specific port?
Thanks for your help.
.Net Developer