I'd be happy with just being able to do regex searches over multiple (2 or 3) lines without jumping through hoops. The mentioned Structural Search for JetBrains' IDE sounds promising--I'll have to try that out.
The feature dates way back to perhaps 2006, per Jetbrains' PDF archive[1]. Jb also updated their structural search UI/UX in 2018[2]. It is possible that users do not buy in the idea of SSR. Alternatively, it may be caused by the fact that Jb SSR's mixed language support. [3][4][5]