I wouldn’t have initially thought that it would “just” maintain the order.
For as long as I can remember I have always “assumed” no order.
And I think of a query of queries as being a whole “new” query.
The fact that inner query was ordered, (or was even a query) I deliberately ignore for the outer query and go back to; “Always assume, no order” - unless you explicitly force one into play via the use of ORDER BY.
However;
If Lucee previously behaved differently for you, I would log a bug as a regression.
Or if Adobe behaves differently (the way you’re expecting Lucee to) - you could log a “compatability” bug.
Otherwise - I wouldn’t think there was an actual issue to address here.