I definitely saw pictures of Tamagawa overflowing on NHK just before it got dark. I haven't heard any news since then, unfortunately. Not sure if the other poster knows more than that.
1) This was nothing for Tokyo this time.
2) it tested the rivers going through the kanto area
3) [it] almost spilled the Arakawa and Tama rivers.
4) That could have been a great disaster!
and got a reply that #3 isn’t correct. Arguing that #4 is correct isn’t in any way a rebuttal to that.