ASEAN countries slightly preferring China to US can be explained by Indonesia and Malaysia, 2 Muslim countries developing a negative perception of US due to its funding and backing of Israel in the Gaza war.
While Singapore, Vietnam, Philippines remain anti-china.
However, its still a very positive development for China as geopolitically, Indonesia and Malaysia are the 2 most important countries in ASEAN.
Indonesia especially with its $1 trillion economy that's growing at a rate of 5-6% will be a major regional player in the future, so it's best for china to push for friendly ties.
US has exposed themselves due to their backing of Israel
HSR was probably a watershed event in Indonesia that not only showcased high quality Chinese manufacturing but is also a source of national pride for Indonesians as well.