@Bimodal_user I’m not a DIY user, so can’t answer on the technical side. But I noticed that within the Phonak app the “wide/narrow” Focus slider sounded less “phase-y” and better for me while playing acoustic guitar. My audi was able to exaggerate that front-facing focus parameter (somehow!) for the sub-program/custom setting we had been working on for guitar so that the app focus slider reduces the rear-facing microphone even more (if that makes any sense). I’m not sure what he did “under the hood” in Target.
When I play acoustic guitar at home it now sounds a bit like I’m staring at my lap, and the sense of directionality has shifted to my (weaker) right ear where the guitar’s soundhole is. Not exactly “natural”, but my sense of latency, warble and unnatural overtones is less distracting overall. My hunch is that turning off the other internal processing parameters that guitarists typically attack (feedback suppression, compression ratios, etc) probably helped more - but de-emphasizing the rear-facing mics helped my experience too.