Of course you want to do maintenance and checks for smooth operations, but failing to do this does not represent a danger in the way it does for normal fission reactors.
There reactors have typically passive, walk away safety by design. If something fails it may cause the reactor to stop producing power, but it doesn't cause a major radioactive incident.
So what if the freeze plug isn't maintained and it fails? Worst that happens is that fuel pours out and into containment tanks and the reactor get shut down. That sucks for the economics of the owners. But it doesn't pose a danger to human health and well being.
Ok maybe the dump tanks are crap and radioactive fuel seep through. Well it will not get very far as it is only liquid while hot. As it cools it becomes rock hard, and get stopped dead in its tracks.
You say pumps need inspection... yeah sure to maintain operations. But again if they fail... so what? That could stop salt from flowing and we get overheating reactor but this will generally cause the chain reactor to stop. If that is still not enough the freeze plug will melt and fuel will get dumped into tanks.
No matter how you twist or turn it, you simply cannot reproduce the kind of accidents that happened at Chernobyl, Fukushima and Three Mile Island. At most you can local workmen who get injured. But you are not going to get the kind of accidents which require massive evacuations.
As for Tritium, I don't know. Do you have any sources that suggests Tritium will be an issue with all Molten Salt Reactors?
But for waste in general, the whole point of a lot of these Molten Salt Reactor is that they can get rid of waste. Why would you not want that? It is not that they produce less waste. No they produce negative waste. Less waste comes out than went in.
Thus if you care about nuclear waste and want to get rid of it, then you should want to build these reactors.
What about long term indeed? We have had reactors today since the 1950s or so. Relative to how much power they have produced, they have an exceptionally good track record.
A few bad accidents have happened. Chernobyl cannot happen with current reactors. Sure Fukushima happened but only one person died directly from that compared to something like 20 000 from the tsunami. Still I care about that. Light Water Reactors are big and complex.
I would like to see a future with less of these reactors, preferable with more renewable energy instead. But Molten Salt Reactors seem like a complete no brainer to me. If the shitty reactors we have today have such such a good track record, then surely Molten Salt Rectors will have even better.
Who will clearn up the reactors when they "dot the landscape"? Seriously?
The problem with your whole approach to this is that you are not considering reactors in relation to anything else. All modern industrial activity and power production leave structures around. Renewable more so than pretty much anything else.
Nuclear reactors already leave a very small imprint on the world. Significantly less than mines, factories, damns and other power plants. Nothing leaves as big imprint as our farming.
Even if you fail to decommission and cleanup these powerplants, they still don't represent a huge imprint on the world. And really I don't see a reason why they should not be cleaned up. There is no past experience that suggests this will not happen.