I did tests regarding Wisps a few months ago, just never cared enough to share in more detail.
Relevant vanish flags for Wisps:
Toggling those flags will toggle the visibility of each Wisp in the overworld, but that doesn't actually have any effect on what can be reported to Vessa.
KWispsFoundArea0* all take values ranging from 0-20 (7 for Area00 -- Jubilife Village), while KWispsFoundTotal is how many you've found across all of Hisui, and KWispsReported is how many Wisps have been reported to Vessa (both range from 0-107).
A cheat to make it to the end of the Spiritomb request would be:
• Set the first 107 vanish flags (MKRG_ID_001, MKRG_ID_002, ... ... MKRG_ID_107) to Bool2 (true)
• Set KWispsFoundArea00 to 7
• Set KWispsFoundArea01-05 to 20
• Set KWispsFoundTotal to 107
Talking to Vessa in-game would then allow you to advance the request to its final section, where you can find the 108th Wisp in the Crimson Mirelands to encounter Spiritomb and finish the request.