lib_fomantic replaces lib_semantic
We decided to move to lib_fomantic for backend and frontend devoloping because there is much more activity (bugfixing and development) as in former lib_semantic.
From 4.3.0 lib_fomantic - a fork of lib_semantic - is used for the delivered LEPSem Theme and Semantic Template.
So you can decide if you want to uninstall lib_semantic or not.
Another reason was that changing code was that easy.
You only have to change your include lines in the templates for example from
https://domain.tld/modules/lib_semantic/dist/semantic.min.css
https://domain.tld/modules/lib_semantic/dist/semantic.min.js
to
https://domain.tld/modules/lib_fomantic/dist/semantic.min.css
https://domain.tld/modules/lib_fomantic/dist/semantic.min.js
and you're done.
For any kind of questions please use the forum.