Because it could easily cross time and space, there was only one Time Dragon in every timeline. There was no concept of the backward order of birth because in the understanding of the Time Dragon, the past, present, and future were just a part of the river of time. There was no difference.
The Time Dragon Countercurrent that Garen had responded to, and the alternate timeline that he had gone to, also had a timeline that belonged to the past.
In the past, the Time Dragons that were still young in Garen's eyes were actually older than Garen in the main timeline. However, in their eyes, Garen was the older and stronger Time Dragon that was born before them.
As for why the Nine-Faced Dragon God didn't exist in the alternate space and time, there was also the reason for the existence of the Time Dragon. Garen had also thought about it.
"Spacetime is different, but no matter what spacetime it is, the river of time is the same.”
