I'm not sure if the following links refer to the same thorium architecture but in Germany there was a test-reactor and several rather hard to solve problems appeared
That was a pebble bed reactor which had issues with high pressure containment vessels and solid fuel. The reactors recommended in the video are molten salt reactors which do not have the same issues.
I think the issues were not only technical, as in P and fuel. The trouble was with those who were responsible for the pebble bed reactor project, and accountancy to the public.
The moment management knowingly blamed accidents on Russians with oversight from the authority, they played away their authority to the right of running such experiments: be it solid fuel or liquid.
People (rightly) assume, that the blatant lies were independent of the phase of the fuel
(AVR and HTR as separate projects make no difference in this respect either). And this is what is biting TEPCO: the series of "white" lies.