I’m not sure if it helps, but try to apply the following “brutal fix”.
Well, you will need to “cheat” the T2K software a bit.
Download and “pack” the current “v5-34-00-patches” source code:
git clone -b v5-34-00-patches root.cern.ch/git/root.git root
tar -zcf root_v5.34.18.source.tar.gz root
Download a “fresh copy” of the whole T2K software but do NOT try to build it yet.
Replace the original “ROOT/*/root_v5.34.18.source.tar.gz” file with the one that you created above (note that the file name must be exactly the same, so if you try to replace the original ROOT v5r34p09, you will need to name it “root_v5.34.09.source.tar.gz”).
Then try to build the whole T2K software.