If you want go for that sort of "live" feeling, you should consider implementing websocket streaming instead of HTTP polling, it will feel a lot nicer for users.
Are you actually ingesting certificates or are you just showing a stream of entries from different logs? I figure the former as nothing seems to be searchable -- and ingesting this data can get very expensive very quickly.
Nevertheless, cool project! I am constantly thinking about ways to turn CT log data into meaningful, actionable streams for others. If you'd be up for working on something together, give me a shout!
As for the 2025h2 logs, these will not be acquiring any newly-issued certificates, but someone might be copying previously-issued certificates from other logs.
a lot of them are related to check24.de