Is there any way to integrate Crystal Report to Webspeed web application ? If not, is there any official source state that it can't be ?
WebSpeed pretty much can do everything a "normal" Progress 4GL program can do so the limits here really should be more about deploying Crystal Report in a web environment.
Checking the official Progress Knowledgebase here gives nothing, neither does the Progress Development Network here so the answer to your second question is "no".