"mostly inconsistent" is correct and can be used in written English.
You can use it to describe a pattern or set of facts that are mostly not in agreement with one another. For example, "The results of the study were mostly inconsistent, as different sections of the population produced different results."
The results of the studies are mostly inconsistent.
This indicates that the secular decay of the axial dipole intensity is mostly inconsistent with the FF+TG condition at the CMB, forming the part of observed SV that is unpredictable by the TG flow.
Although covariates significantly differed inside and outside the clusters, patterns of differences were mostly inconsistent.
Although some interactions were noted, few were statistical significant, they were mostly inconsistent and not affecting the main outcome.
Few and mostly inconsistent records are available for laboratory confirmation of the malaria prevalence among the presumptively diagnosed patients without any evidence that diagnoses of anaemia among the patients were ever conducted in patients seeking malaria treatments.
Costs associated with pregnancy coincided with the diminishing of their own ability to secure income and came at a time when partner support was mostly inconsistent, if provided at all.
Even with these advances, certain cognitive limitations remain, mostly involving inconsistent application of recently acquired cognitive abilities.
Even with these advances, compared to adults certain cognitive limitations remain, mostly involving inconsistent application of recently acquired cognitive abilities [ 25].
Muscle activation patterns were included in this review as they represent a specific type of movement pattern and are reportedly linked to therapeutic change with appropriate interventions Effect sizes for muscle activity pattern changes were inconsistent, mostly non-significant and generally small to moderate in size.
It seemed so for long spells, despite flashes of brilliance – mostly from the inconsistent Toni Kroos.
His command had been suspect, and major league hitters had mostly ignored his inconsistent curveball and changeup.
