The fact you have three digital pedals in series on one insert may be complicating the adjustment process. Have you tried adjusting the latency for just one pedal? Try, for example, to just use the Boss or CB in one loop. Are you able to make a functional adjustment?
Something to keep in mind, every time you create a parallel path you’re also creating a copy of any dry signal at the split point. It’s generally the case that some effects in a parallel path will need to function in kill dry mode (or be set fully wet), so it’s just wet effect only, the way effects busses are applied in live sound or how effects busses work in a studio mix where you’re not mixing copies of dry signal together over and over. Any Program where you’re running these insert effects in parallel, I would try running some or all of them fully wet so the dry signal on the H90 path is not causing phasing issues with any dry signal going through the external path.
