the syntax is acceptable, but some poor choices went into writing the sentence:

1) 'flooded on to' and 'flooded onto' have different meanings, and the author most likely meant the latter but wrote the former

2) '...jubilation that...' [already discussed here].

3) '...embracing... journalists following...' this is ambiguous. it can either mean that the journalists were following today's events or that the embracing happened after a previous day's events.

4) '...for kyiv...' this is a device called metonymy that this writer used out of habit (e.g., writing 'from washington' to mean that a statement came from the american government). the problem is that the sentence describes events in a ukrainian city that is not kyiv. in other words, it makes it sound as if kyiv was just liberated and not kherson.