I posted an English-dubbed version of the news clip with the boasting Zhang Shuguang in an earlier diary of mine, though without that particular boasting, here it is:

What this means is that clearly they were making modifications to optimize from the very beginning

Well, without basis in any details, that's a rather far-fetched assumption from what you yourself call boasting. You are assuming extensive modifications in the timespan of a few weeks by engineers without prior experience with these technologies and this speed region. Furthermore, that boasting was on a record run, which doesn't say anything about regular service - limiting top speed in actual service to 340, then 330 km/h is more instructive.

So it is not clear if the modifications and research goals are still "planned", or are already (partially) realized.

The CRH2-350 and CRH3-350 are code-names for the new batches ordered in March and September 2009, to be put in service 2011-12. So no, this is not about stuff already applied in the existing sets, but about on-going research.

_{*Lunatic*, n.
One whose delusions are out of fashion.}