I think the scavenge tube is fed by a tray, or gallery, responsible for collecting hot Oil at the 'bottom' of the bearing case. I think also the challenge for Rolls is to detune the Thrust case from the LP shaft, keeping in mind that Thrust is borne in other areas besides the Ball Bearings. There are struts in the IP case that connect further forward, assuming a great deal of forward push from the engine.
De-Tuning I think will prove insufficient to correct the problem in the 900. To isolate massive vibratory impetus would more than likely involve strengthening the Shafts by adding metal. Inside Diameter? Outside? Both? This motor is already at maximum relative to clearances, weight, and power. If all it meant was adding weight, easy peasy. There are dimensions that actively resist any solution by addition. These dimensions likewise prevent subtracting structure without losing Thrust. Losing Thrust at 72klbs prevents puffing out the rest of the 80k that was sold, and paid for.
Least possible of all is to change the architecture. The architecture was modified already, and away from a proven model. Go Back?? As Woj points out: Back there lies the 800.