Thanks for the report. Sorry for the late reply. I didn't check the wiki messages. Did you edit the wiki page to reflect your findings?
Sorry now for my late reply... I did not update the wiki about grantlee. In fact I could not complete the rest of the building at the time. I am going to try building KF5.17 in Debian Testing now. If there is anything that is not reflected in the wiki and I succeed the building, I'll share it here and on the wiki. Regards!