Talk to the characters.

[Shoal]

i thought they made him a mint

[Bluelantern]

i thought they made him a mint

If Lynia merely hears about Wishcoins there is no force in creation that will stop her until she gets minted.

[Shoal]

mark will be a better mint

[DanielH]

Yes, I hope we get to see that happening in Effulgence relatively soon. The status report doesn’t say what landmark Nexus needs to hit before then, though (and I wouldn’t recognize it anyway because I haven’t read Vor canon yet).

[PlainDealingVillain]

There's a big thing with an attack on the cloning process on Jackson's Whole that would need to happen before wishcoins to make Nexus stay close to canon (and Miles goes into a very different stage of Miles-ing after those events, so it's a big change). After that it's probably up to personal preference, since the next interesting canon events after that result in Miles meeting and (eventually) marrying Ekaterin, and he's too monogamous for that to happen.

[Nemo]

Spoilers for Angel season 2, but Tamara probably wants as many of those as possible anyway and would consider this important, so:
Wolfram and Hart has a spell to bring back a dusted vampire. Bella would be happy to capture the five sacrificial vampires, and the resurrected one comes back as a human complete with soul.

Not that anyone relevant has any way of knowing about that, but it's a thing that exists.

[Marri]

Hmmm. I've only seen Buffy, not Angel, but the wiki makes it sound like the spell is just to "summon a great evil from the vortex of Hell" and that it was a human souled Darla was basically an accident?

[DanielH]

I haven’t seen either Buffy or Angel (it’s on my ever-growing list), but I would be very surprised if no Buffyverse magic could reliably (by the standards of Buffyverse magic, anyway) bring back a dusted vampire. Whether Tamara would have knowledge of or access to it is another matter.

[Bluelantern]

I haven’t seen either Buffy or Angel (it’s on my ever-growing list), but I would be very surprised if no Buffyverse magic could reliably (by the standards of Buffyverse magic, anyway) bring back a dusted vampire. Whether Tamara would have knowledge of or access to it is another matter.

*whispers softly to send hypnotic messages* "Buffy should be the priority"
Buffy wikia sounded vague enough about it. We do know that it is possible to use magic do ressurect vampires anyway. Maybe becoming a vampire briefly would cause some problems for Kevin

[Nemo]

They did have an ongoing Project Mess With Angel, so a Darla would be too much of a coincidence. At the very least they can pick their target. I even doubt whether "must be evil" is a constraint, because ensouled Darla is evil but she isn't rampaging hellbeast evil. (Also I can't picture it summoning anything too powerful to put down if everything goes wrong, merely because a few vampires is a pretty small-scale sacrifice.) The prophecy about that specific use of it definitely expected something evil, though.
Maybe the spell only summons things from Buffyverse Hell, so the evil requirement is because the target has to be there in the first place? That might make Darla a possible summonee but not Kevin.

There's also (Buffy S6E1) the spell Willow used to resurrect Buffy, but that one is well established as a Bad Idea.

Obviously both would be classified as dark magic that no Watcherlike person would tell Tamara how to perform even if they knew.