Hi there, I'm Matt Sergej (do call me Matt, please) and can help you with Leaflet map -
you want just to add a rotation? What about editing markers - it appears you have created them with a tool that exported the javascript to create Leaflet map elements (circles). This could be done in a script, with data from Google Sheets table for example but I believe you have editing in place.
If it's only a map rotation to add I will lower this bid. You also have FlyTo function used in your example so please be specific.
Otherwise I'm a webmaster and developer for 26 years, scripting web maps more extensively in last 7+ years.
Regards and hope you're safe,
Matt