In any case: yes, obviously. Although Germany works both within the EU and the UN climate process to find collective solutions allowing other nations to also reduce emissions. China is actually becoming a positive example these days, installing vast amounts of renewable energy.
Phasing out coal in Germany obviously makes for a good argument in such talks. But even if it doesn’t, not burning coal and buying from China is still strictly better than burning coal and buying from China.
It’s sort of like smoking and getting regular exercise is better than just smoking.