Can you, with certainty, connect CLS63 with the other accounts?
It can never be certain. But in this case, I'd say that the IP-log picture alone makes me 80% confident that they're linked, and that's on top of the other stuff.
There
are ways that two different people could share the same exact IPv6 address. They could use the same Tor exit node, the same web proxy, the same public WiFi, the same library computer, etc. That's why I didn't
just find a matching IPv6, but manually looked through each full IP log (with geolocation data going back years), looking at the picture in its totality. It
is important when identifying alts to approach it carefully and skillfully, because false positives are very common. For example, Pakistan is a very tricky region to identify alts in because it's common for tens of thousands of different people to get the same IPv4 address; so if you're identifying alts among Pakistani users, you have to know this and apply special care. (That's not to say that it's impossible to identify Pakistani alts: you just have to pay more attention to
timing and
shifts, rather than pure shared IPs.) The possibility of creating false initial impressions is why I generally like to only look at IP logs
after there's already some sort of preexisting suspicion for a pair of users.
That said, it's not ever
normal for unrelated users to repeatedly share the same 128-bit IPv6 address, even if it's not totally impossible for it to happen. CLS63 shared the exact same 128-bit IPv6 address with 7 users (in a sliding +/- 7-day window), often repeatedly. Most likely these are all alts, though I only posted the ones that I had very high confidence in. If I do the same check but matching on the /64, it'd be 270 users. Looking at all forum IP logs over the last 90 days, the specific /64s used by CLS63 have an average of 1.0247 distinct users per 128-bit IPv6: so it's not at all common for users on his networks to share complete IPv6 addresses.
Also, can we now expect such involvement from you in similar cases in the future?
I have historically published alt-check info in these sorts of investigations from time to time, and I'll continue to do so from time to time. Though like I mentioned above, IP evidence should ideally be used as a
final step to confirm something that is already strongly suspected.