Couple things to note, even if you limit how fast you join channels there will still be a maximum number of channels you can join as there is a buffer of messages Twtich is sending your connection and if you’re not reading from that buffer fast enough you’ll be disconnected. Since you’re joining the channels with the most viewers you’ll have a high chat activity so would likely have to use multiple connections.
Secondly, Chatterino is designed as a chat app for end users, where as you seem to be programmatically joining channels, and specifically mentioned ‘crawl’, which has the connotation of web crawling and gathering data.
Through the API this may be okay to some extent but if you’re joining chat channels to gather data without any permission from the channels involved then you’re potentially breaking GDPR if you store any user data, and if you’re not storing user data but monitoring things like chat activity, or measuring any sort of metrics, then that could fall under the category of ‘research’ or ‘marketing’ which are a violation of Twitch’s Developer Agreement unless you enter into a separate agreement with them.