Hi Seb. As Makara says, we don’t have a way to import the Ukelele files. If you have the original
.keystrokes file that was sometimes used to create a Ukelele keyboard then, that would be easy to manually use the rules for Keyman.
If the Windows keyboard in your zip file is designed the same as the Ukelele keyboard, then you can use that. If you have the keyboard installed, go into Keyman Developer, click on Project/New Project, select Import Windows Keyboard and then scroll down until you see the name of your keyboard (QWERTYThai).
It will then import the keyboard. You will need to do some work on making sure the ID is what you want, copyright, documentation, etc, but at least a lot of the initial work is done for you.