Yes, this is an existing problem that I have been meaning to create a JIRA for.
Basically the ejbql attribute is defined as a String which means the EL is evaluated when the EntityQuery/Query component is created from components.xml. Any ValueExpression result is then set directly into the ejbql String (which is why you are seeing this behavior).
The fix is changing the ejbql attribute to a ValueExpression type and using the getExpressionString() to retrieve the original ejbql String when parsing the ejbql.
I will post up a JIRA and get the fix in as soon as I can :-)
Hope that helps.
Ah, yes, I thought it was something like that. Haven't used entity-queries with parameters before and didn't quite get the source code to match what I thought it would be doing. Thanks for the info.