That's a lot of great questions that I hope there are answers to. But from the article:

That water will contain about 190 becquerels of tritium per litre, below the World Health Organisation drinking water limit of 10,000 becquerels per litre

So it's about 2% of the limit for drinking water. Assuming there's some correlation between drinking water and ocean water for acquatic life, I think it's reasonable to assume that this is a trivial amount of tritium.

Yes, some aquatic life is likely to be impacted, but whether that amount is actually statistically significant is another question entirely.

Despite assurances, some neighbouring countries have also expressed scepticism over the safety of the plan, with Beijing the biggest critic.

Here's an article where Japan claims China releases many times more tritium than Fukushima will. I don't have access to this article, but if you do, it seems like it should be useful in comparing with the claims in the previous source.

So I think it's a lot of FUD either from China, anti-nuclear power groups, or both. To me, it seems like something that should probably be studied, but not worried about until we actually have reason to believe it's problematic.