No, it does not work this way
There is a difference between the use of the criteria and the Locate spell itself. It is not likely that you can utilize the knowledge that lead can occlude the object as a means to locate the object by Locating the lead.
The key phrase that my suppositions are based on is (PHB 256)
Describe or name an object that is familiar to you.
- If an object is not in range, then Locate Objects will return a null result.
- If the object is in range, but is blocked directly from you by lead, then Locate Object returns a null result.
- In order to use the criteria as a workaround for the Null Result, the caster would then have to use Locate Object on the lead object that is blocking it - which they wouldn't know of and therefore not be able use Locate Objects to find.
However, if you do know that the Object is obstructed and be familiar with and can describe the lead obstruction, you could use Locate Object on the obstruction to then find the object.
Specific example from OP
A lead object that is blocking a direct path between me and an item that fits criteria X, Y, Z.
If you can describe the object you are looking for, then Locate Object can find it. A general description doesn't fit something you are familiar with; it is the difference between a "water bottle" and the "blue nalgene with a nick on the top" water bottle. One is an oject - the other is an object you are familiar with.
In this case, if Criteria X,Y,Z describe a specific object it would work. But if you are guessing, then it is not something you are familiar with and the spell wouldn't work.
If you are interpreting it as(bracketed info provided by me)
A lead object [that I am not familiar with] that is blocking a direct path between me and the Mona Lisa.
You may know something is there and what it is constructed from, but you don't know what the actual object is. And if you don't know what it is(aren't familiar with it), then you can't Locate it.
The problem as I currently see it the caster trying to find an object has to know whether or not the object they are looking for simply isn't there or if it's obstructed by lead. They are free to recast the spell as many times as they like, but the assumption that the object is there but obstructed isn't necessarily true. And Casting for lead objects could easily provide false positives. Then the DM either has to provide those false positives or "Just allow it to work", in which case - why have the restriction at all?