The ExFighter

[Anthrowhale]

Saying that initiative ends isn't reasonable if one side is still stalking and studying the other, as you need to go round by round to see if Ex stumbles upon the wizard, or the wizard stumbles into Ex.

First, you haven't established the ability to stalk and study.

Second, initiative generally ends when order is no longer relevant. If you can stalk and study, it seems unlikely that it matters whether Ex finds you in round 35 or round 36.

Do you have means to disappear from the wizard that don't involve fleeing altogether?

By default, size fine and (presumably) >100'.

It's also easy to switch AMF for incorporeal and hide underground and/or add Will-o-Wisp Invisibility.

It's also possible to swap high Diplomacy for Hide in the build.

It's not reasonable to claim that getting blanketed by an AMF isn't an "impending danger," and thus it would trip foresight.

I disagree with this. Foresight is not independently intelligent, so it cannot make deductions about what the approach of AMF means. Hence, the test is only "is AMF in itself dangerous", and the answer is "no" because the wizard would survive fine in an AMF.

Furthermore, any wizard with persisted emanations or auras would notice the AMF before it got to their square even without foresight, if nothing else by their forceward, anticipate teleport, consumptive field, stormrage, or other persistent effect surrounding them starting to not function.

Whether or not the approach of an AMF is detectable in this way depends on details. For example, is there a dieing thing nearby? If no, then the lack of function of Consumptive Field isn't that obvious.

The AMF, LightningStrike, and high initiative are there not because a wizard can't penetrate it, but rather because penetrating it consumes class levels, actions, or other resources. ExFighter doesn't have access to the same action economy breakers as the wizard, so this seems like an important effect to take advantage of.

Trollbane doesn't ... work like a poison ...

This is contradicted by text. "Trollbane functions as injury poison (DMG 296) ...". More generally, there is precedent for simalogues substituting for the real thing, for example with virtual feats.

The other problem with Trollbane is that you actually have to do damage with it.

I don't believe this logic works, because triggering Trollbane just requires "Any creature struck by a weapon that has been coated in trollbane..." so the resolution sequence is:
(1) Weapon strikes target
(2) Trollbane activates
(3) Weapon delivers damage
rather than (1), (3), (2).

...Knowledge (arcana)...Gather Information...Diplomacy...

Yes, no, yes. I'm not convinced that Gather Information is required to hire someone.

Antimagic Field

You misemphasized:

Artifacts and deities are unaffected by mortal magic such as this.

If the AMF is not produced by magic, that sentence is inoperative.