This seems very worthwhile, good on you for forking and resurrecting this.
It might be worth you updating the about page to say what lightly is - I had to google and find the original git to work it out. I’m still not even entirely clear - this seems to be more than a theme? As well as retheme Breeze It also seems to expand on what Breeze does?
Your project can stand on its own merits rather than just referencing defunct projects - that might help future new contributors better understand what the ask is and get then more interested / excited about helping?
As someone who drives to and around Wales multiple times a year, it’s a poorly thought out and implemented policy.
Many people speed and break the limit, particularly on main roads, and it’s lack of popular support is an issue in itself.
The policy could work if the speed limits was reverted to 30mph on bigger roads but local councils and the Welsh assembly blame each other for the issues.
There is also little enforcment at present - that is changing and once people start getting fined for breaking the 20mph limit it’s likely to become much more unpopular.
It could have probably been implemented successfully and with popular support with more careful designation of 30mph roads. It’s a failure of politicians rather than the idea itself.