Error: failed to determine if primary:kostum/fonts/gobold high bold.tff is child of primary kustom:java

Uninstalled KLWP, KLWP pro, KWGT and KWGT pro. Deleted kustom directory.
Downloaded KLWP APK 3.58 from Installed. Choose folder dir, New folder 'Kustom'.

Downloaded Theme.KLWP. Copied to Kustom/Wallpapers. Import theme in KLWP.
Try to save it. Still same error...

I was having the same issue. Had to find a gobold high bold font download online, and put the font file in the font folder within the kustom folder. Make sure the font download reads as Gobold High Bold.ttf

After that I was able to save. Hope it works for you as well.