I've just discovered that XSLT 2.0 allows you to define your own functions -- info and examples here. Saxon 8 supports this (details), so we should definitely try it out. I could create a function which strips off the leading article and puts it somewhere else, and call that function, passing it the title of the document, both as the sort key and as the rendering instruction, so that we'd get articles sorted according to titles without leading articles, displayed in the same way. This should definitely be part of teiJournal's code.