Have you tried the 4-pass (i.e. 3-pass + fast) algorithm in RT? It surely helps with the crosshair type of artifacts where they are the most visible (in the flat, low contrast regions).
Three years ago ago, I compared different algos including the FDC (Frequency domain chroma interpolation for xtrans sensors: good enough?), but IIRC, FDC tended to create strong color bleeding.