For cross compiling KF5 library ktexteditor a native variant of katehighlightingindex needs to be build, installed. A related review request has been openend at https://git.reviewboard.kde.org/r/128971/. After submitting a related patch the related KF5 library has gotten a major refactoring which requires to reimplement/update this review.
katehighlightingindex has been moved to syntax-highlighting repo. A similar patch has been reviewed at https://phabricator.kde.org/D7102