x1 is a bad/poorly-made lujvo with issue x2, bad according to x3 and by standard x4
The badness need not be an error per se; it may merely be some feature (x2) that is not desirable or relatively preferable. For example, perhaps the terbri structure is not predictable/regular/algorithmic, or the lujvo is very long, or the lujvo is not the highest-scoring lujvo (for some fixed tanru construct) according to an algorithm/standard. See also: srejvo.