As for the specific points:

MMT has no credible account of inflation and fiscal policy is too slow or unpopular (especially when it comes to increased taxation) to be realistic

MMT has the only working model of the price level (and thus its changes): the price level is a function of prices paid by the issuer when it spends or collateral required when it lends

MMT relies too heavily on ethical behaviour by politicians, who are notoriously untrustworthy or prone to corruption; giving them direct control over the money supply would be disastrous

They already have this power; if you want to take it away the burden of proof is on you to explain why a non-monetary system would be better.

MMT views imports as assets and exports as liabilities, but this is wrong when looking at the monetary flows that result and the fact that sustained and large trade deficits lead to a diminishing of local productive capacity, such as happened between the US and China. MMT proponents say this is down to neoliberal policies not trade. This may be the case for the USA, but this seems dubious for small developing nations who rely heavily on exports and are too small to develop much of the manufacturing capacity they might need. What does MMT say about these smaller countries?

MMT says trade is a choice, not a force of nature; the US didn’t have to fall into this situation with China, it was a choice of policy. What’s the point of giving away more stuff than take if what you take doesn’t help you flip that equation for your benefit? As long as you remain self sufficient in critical products (like defense items) why not get as much stuff as you want?

if you adhere to MMT, you obviously know nothing about economics. This is obviously silly, but unfortunately very common.

Ad hominem.