I think this is an issue I have seen before (with the same server you are using). I think the server does not recognize the useragent string that it is getting from Enterprise Browser. You can change that string in Enterprise Browser to test this, but what I saw in the past is that if you change it, you are likely to break the Enterprise Browser features (scanner, etc). I think the eb*.js files look for something in the useragent string to know that the page is running on Windows CE so that the proper EB Objects get loaded. I think the problem we saw in the past was that the trinidad server does not recognize "Windows CE", so it fails. Not sure if there is a way to fix this on the server end (so it recognizes "Windows CE", but if so, this would be the right way to fix this. I think the customer in my case edited our ebapi-modules.js on his server so that it only checked for "Windows", not "Windows CE". This worked for him, but not a great solution, since you would need to do it again any time you update that file, and also I'm not sure what will happen when someone loads that page from a regular Windows machine that is not running EB and does not know what to do with the EB objects.
JSPX pages are supported.
It may be because of server configuration or a bug.
Please share the server configuration details.