Yes, China urgently needs a radical solution to this problem.
Either immediately raise births or introduce immigration from East Asia or both.
Can you imagine what this year's births will be; what if they fall below 10 million?...
Something needs to be done urgently
I would prefer to first try radical domestic measures before going the immigration route from the region (not immigration from the whole world)
Immigration from the region is a non-starter. Not even accounting for the lack of Japanese immigrants to anywhere in the world historically (small populations migrating to Brazil and the US are exceptions not the rule), you have to take into account:
1: These populations, in Korea, Japan, Singapore, Taiwan are experiencing fertility crises themselves. Some of these places are already in negative population growth aka decline. South Korea just got there in fact.
2: Even if these populations were both culturally amenable to immigration and had large surpluses of young people (they have neither) , you still have to deal with the fact that China is a gargantuan nation in population size. I don't think people fully realize the scale here. If those other conditions were somehow met, it would still not put a dent in the issue.
Basically, even if China could get young Japanese, Koreans, Taiwanese to somehow migrate at fairly high numbers, the changes would be marginal if you consider the population size of China 1.4 billion. Mexico alone is almost 40% the size of the US in population. There is no country like that for China nearby, except India. Unless you want to welcome millions of Indians in every year, then immigration is a non-starter. The only way is for Chinese people themselves to remedy this.