I am wondering if this course is up-to-date with latest version of Solidity and Remix. I watched the first few videos and it seems like it uses an old version of Remix
For Solidity it’s up-to-date yes. Smart contract 30 uses Solidity 0.5.0. It doesn’t matter that the latest version of Solidity have a higher minor version number (ex: 0.5.8, 0.5.9, etc…). Solidity follows SemVer (semantic versioning), which means that there will not be any backward incompatible change as long as the middle version (the 5 in 0.5.x) is the same.
As for Remix, yes Smart contract 30 use the previous version of Remix. However it does not matter because the new version of Remix works exactly the same way, except that the UI is different. So you will be able to follow the videos of the course without any problem.