I'd like to be polite about this, I really would, but it's simply not possible.
Test Dummies is a work of seemingly infinite contempt for its source material. This is not in itself a bad thing; one could make that comment about, say, Nobody Dies or Methods of Rationality. The problem is that Test Dummies doesn't DO anything with that contempt besides display it. It doesn't try to rationalize the source material or to reconstruct it in a manner that covers what it sees as the holes in it. It just points and cackles.
The knowledge of canon on display here is poor; in a world where we know that B-ranked mages can simply soak anti-tank rounds from Subaru's Barrier Jacket doing exactly that in Soundstage X, this story decides that an AK-47 is sufficient to threaten what's arguably the single most powerful mage in the setting.
The treatment of the canon characters and their skills and organization is the most blatant display of contempt I've seen in written works in a long time. The author has taken the worst possible interpretation of the TSAB that one could even pretend makes sense and used it as a fact, a fact which the organization having existed for seventy years when Striker S rolls around makes hard to accept.
The writing is obsessed with being awesome and packing in references, to the detriment of the plot, the characters, and pretty much all other elements of storytelling. While not an uncommon affliction of more modern fanfiction (Nobody Dies again), Test Dummies pushes it to the point of losing coherence.
It suckers you in by hiding its poor qualities by not dealing in the world it's set in for the first few chapters strongly, but once it begins to they come to the fore painfully.