Sharing Filters

You should be able to customize the style of the sharing buttons with some custom CSS. Here is a good example:
https://halfelf.org/2013/sharedaddy-genericons/

If you want to completely remove the existing sharing libraries, and use your own custom styles and Javascript instead, you can follow the instructions here:
https://jetpack.me/2013/05/03/custom-sharing-libraries/

If you’d like to see more specific filters, do not hesitate to give me more details!

You can also create tickets in trac and contribute there.
https://jetpack.me/contribute/
https://plugins.trac.www.ads-software.com/newticket?component=jetpack

I hope this helps.