in Death Masks she is directly, and personally, ordering Elminster. She seems to be rapidly regaining power with the fall of Shar's Shadoweave scheme
Given the completion of the new Host Tower of the Arcane at the hands of one of her chosen and the creation of a kind of Avengers of Wizards (A netherese lord, the most powerful drow wizard, a cloud giant, and one of her chosen), and one of Mystra's Chosen literally running waterdeep at her command (again, death masks), it stands to reason that she is rapidly gaining power, because she visited Gale in person (citation: Baldur's Gate 3, Larian Studios)
MY GUESS is that Gale is a potential Chosen, warranting her visiting him personally
No, as you said her influence is defined by the actions of her Chosen and not herself. One of her chosen must approach the mortal champion and first be offered this knowing fully what he is committing to. Ao directly forbade gods to influence the world in any other way. This was a direct consequence of the time of troubles, the Era of Upheaval and the Second Sundering.
Think about what you are saying very carefully. You are saying Mystra directly contacted a mortal and forced him into a contract without explaining anything when more than enough of her power has become capable in order to do this and either:
a) Gave him a task that he failed, invalidating him as a potential chosen.
b) Approves of his thirst for power despite this being the thing Mystra hates and has suffered at the hands of AND places all the restrictions that currently exist on magic.
You are saying that you think that MYSTRA trusts a power hungry mortal and sought him out and still seeks him out despite his added on ineptitude and the damage he is doing to the balance of the weave with his subsequent actions. Please.