Thank you for your interest. Note that this is the first time I'm showing Love Text, so I'm still recieving feedbacks if it compiles/runs or not on different computers. So, if anyone are interested in making test, please, go on!
1. Multi-platform is very possible. But I will make it stable on Linux first.
2. Yes, it provides highlighting and all the theming stuff. Plus, you can set a custom Gtk theme different from the system theme, so the program will look unique.
3. It uses Lua 5.2, but once LGI give support to Lua 5.3, Love Text will adopt the 5.3 version, too.
4. While creating Love Text, I'm trying to grab good features from others text editors and avoid their pitfalls.
For example, gedit has a lot of features, but is hard to create plugins, is bulky and crashes a lot (at least with me); Mousepad is stable but lack features; Sublime Text is beautiful, but is bulky and closed-source.
I have some short-term plans, like creating a minimap plugin and command palette (like we see in Sublime Text).