Seems like there is some mess up with the QT dependencies and/or the recipes for Gcompris (mix of both with 100% chance).
You need to install qt5_tools to get the lrelease executable and other tools, i guess.
So the recipe compiles if you add:
to the BUILD_REQUIRES section of the recipe, and go ahead (either install it with the depot, or use the autodependency flags).
Unfortunately for my test system, this collides with llvm-clang versions greater than 6 (i.e 7), so i had to uninstall em to get version 6 and qt5_tools installed.
Edit, with the same patches that Mr Duval did (in same files, different lines), 0.91 works nicely in the beta version:
Uploaded the new recipe + patches to my github: PhHaikuRecipes
@extrowerk Can this be moved to the official recipe git without having to make a pull request for those 2 files?