I have no trouble using off-the-shelf Bookerly on my Kobo Clara HD and Kobo Libra 2. Just make sure you give the files these specific names on the device:
Bookerly-Bold.ttf
Bookerly-BoldItalic.ttf
Bookerly-Italic.ttf
Bookerly-Regular.ttf
The font versions I use came from Amazon here:
https://developer.amazon.com/en-US/a...nes/typography