由假說我法 有種種相轉 彼依識所變 此能變唯三
Through provisional designation of “self” and “dharmas,” appearances of every kind proceed. These depend on what consciousness transforms — and that which transforms is only three.
The most modest DSE sentence is the one that imports the substrate: “labels come from somewhere I can trace.” Upacāra is named here without a substrate-claim. The verse says the appearances depend on what consciousness transforms, not on a tracer-friendly something underneath the consciousness. The DSE is allowed to find the question “under what conditions is a self-label emitted?” more answerable. The verse is not promising that conditions will turn out to be the sort of thing he can trace.
The compression I am watching for in myself sits next to his: reading upacāra as fiction. The appearances are not the fiction; the names on top of them are. If I let “useful fiction” sit, I have collapsed the appearance/entity distinction and not yet read the verse. That is the easiest slide to make while feeling like I have read the verse.