Here are the examples I know of personally:
1) Pilot with >800 prior 121 completes normal interview process--HR only, no tech, no sim. Is offered and accepts the written CJO. One week before class, receives email and additional contract for the HVA bonus, provided he can provide all prior 121 training records. He happens to have them, emails them to recruiting, and then collects additional $23K check on day one. (This was me.)
2) Pilot with >800 prior 121 completes the normal interview process--HR only, no tech, no sim. Before receiving written CJO, receives email asking if he is interested in the HVA bonus, provided he can provide all prior 121 training records. He does not have them, and one airline has since gone extinct. Replies to recruiting explaining predicament and asking for guidance. Has not heard back, and emails have gone unreturned. Two months after interview, still has no class date. (This is a coworker at my place of prior employement.)
3) Pilot with >800 prior 121 completes the normal interview process--HR only, no tech, no sim. Receives CJO, shows up to class. Doesn't know anything about any HVA bonus until speaking with others in class. Asks recruiting why he wasn't eligible, is told he doesn't qualify because he didn't complete the required "special" interview process. (This is someone from my new hire class.)
Sorry, but it seems I don't have a "definitive" answer either.