Problem with Channel Subscriber Check

You can’t. IRCv3 tags require someone to speak in the channel.

Chatty only shows badges next to users when they speak.
Chatty may then also store/cache that data for later display. But all it’s doing it storing it in cache for later and thus likely not 100% accurate, but close enough for chatty’s use case.

You need to get the broadcaster to grant access but then visitng a link and clicking [accept]
Which’ll then provide an access token that is valid for the broadcasters account.

This is basic oAuth.

oAuth allows other users to visit your website.
Click a link,
Which then grants access between their account and your client ID.
Your webserver then captures the resultant access token.

So
In order for you to read liriks subs then lirik needs to visti your oAuth flow and grant access
In order for you to read ninjas subs then ninja needs to visti your oAuth flow and grant access
In order for you to read your own subs then you need to visti your oAuth flow and grant access

For the streamers I work for I will send them to BarryCarlyonBot which will ask the user/broadcaster to authenticate/grant access. My server will capture the resultant access token and store it in my database for use.