I think the phantom availability is only particular to LH F award seats (correct me if I am wrong). For all other alliance partners such as LX, AC, NH, etc., if UA shows availability, it's also available on ANA tool, and it is bookable with the agent. I had one agent who bluntly 'lied' about AC's availability when both UA and ANA searches showed YUL-FRA being available in C. But subsequent call took care of that issue.

Also, it used to be that with LH F, if you see availability within 14 day window prior to departure in UA's booking engine, it's 100% available. However, my recent searches have indicated that it's a mix and match (ANA cannot search within 7 days, so I cannot comment on matched availability <7 days prior to departure). But if LH flights are beyond the 2 week period and UA shows it's available, it is 100% phantom availability.

Lastly, just today, I was trying to use ANA tool (with greesemonkey code enabled), but I wasn't able to access partner award search page. So, it seems like ANA fixed the greesemonkey 'cheat.'