Re: the overal discussion of overall CC numbers... It's already completely impossible for Kakudou's tweet to be accurate at this point. First of all, as others have pointed out, the tweet itself is mistaken about timeline, placing Hikarigaoka in '96 rather than '95. Regardless of that, though, no aspect of his comment can be reconciled with the series.
1. He says "in 1999 there were eight people," which is patently false with all the other Chosen Children who we know about during that time.
2. Even if we give the benefit of the doubt and readjust his statement to be starting from '95, that would make 16 Chosen in '99. This is also impossible. The Adventure kids make 8. Ryou makes 9. Daigo's group of five makes 14. Menoa makes 15. Meiko makes 16. Wallace makes 17. Et cetera.
3. Could you further correct his statement to mean that there were two Chosen in '95 leading to 32 in '99? Sure, but now his original statement is wrong on multiple counts either way. That can't be considered reliable info. It would also mean that the earliest Daigo's group could have gone to the Digital World is '97, and it's simply not possible that Maki was a preteen girl in '97 and then a university-graduated government official in 2005.
4. Hikarigaoka cannot be the first time people had Digimon partners. Even if we ignore Daigo's group — which we shouldn't, because again, they are too old for their adventures to take place post-Hikarigaoka — Pipimon was most likely Oikawa's partner before the Adventure Chosen were even born.
5. There is no way to use the Digital World's time dilation to solve this. People become Chosen Children before they ever enter the Digital World, that's how they're able to go there in the first place. If the "doubles every year" was influenced by the Digital World's time passage, then the entire world would be Chosen by the time Adventure started.