You could tell them you'd be happy to lay out the liens in order of filing as an indicator of priority... but honestly, so long as you're disclaiming responsibility for the review and providing lien positions as a starter, you should be able to identify based on relevant state law which liens have a position elevated beyond order of recording and prioritize those, correct?

I'm not sure I see the source of your objection to performing that sort of review, particularly when your hourly rate for doing so could be quite large, and the review itself is rarely going to require a heightened degree of expertise and expose you to virtually no liability to anything other than complaints from the client that you'd have to field in the event you get the positioning wrong and they (inappropriately) rely on it.