> The two-party system is fine.
No, its not, as anyone who has paid even a slight amount of attention to the study of comparative government among modern nominal representative democracies would recognize.
> We have to be honest about the fact that parliamentary systems can give massive power to a tiny fraction of the population when that small party becomes the deciding vote.
Parliamentary systems can be two-party and multiparty systems do not need to parliamentary, so you are starting with a false dichotomy. And the problem you describe is less often a problem with multiparty systems (parliamentary or otherwise) than two-party systems, because the reliance on ad hoc coalitions means that there is much more likely to be the option of replacing a faction that is leveraging its marginal role in creating a majority to wag a coalition that is a small part of, whereas a small faction within a major party in a two party system that is crucial to maintaining a partisan majority cannot practically be defied without the rest of the party surrendering its majority, giving it much more power than a minor coalition partner in a multiparty system.
(Parliamentary or semi-presidential systems are also generally better than presidential systems, but that's a whole different issue from the multiparty vs. two-party issue.)
> The problems with the USA political system are: electoral college, senate being 2 votes per state, and the supreme court being 7 people for life.
The first two of those are also problems (though actually being a Presidential system is a bigger problem, and a problem without which the electoral college would be moot.) The third is simply inaccurate.
> But nothing can be done about the last two now. Especially now that the Supreme Court made a decision limiting how amendments can be ratified.
The Supreme Court decision on how amendments can be ratified (basically, however Congress decides) does not substantially limit what amendments can be passed. And it is the first two are set in the Constitution, the third (even using the correct current number of 9) is not, and can be changed (that the Supreme Court exists and that federal judges have lifetime tenure as federal judges are set in the Constitution, the number of seats on the Supreme Court, whether that number is fixed or floating over time, and the tenure of judges on the Supreme Court separate from their tenure as federal juddges is not; all of those can be changed by statute. If Congress wanted to make Supreme Court justices appointed for a fixed term of years from among the set of lifetime federal judges, that would be possible. If Congress kept lifetime tenure for justices, decided to have one appointed every 2 years regardless of the current size of the court, and have the Chief Justice appointed for 4 year terms from among the sitting justices, that would work too.)