Weird characters in the webtool

I deployed the docker image for lpar2rrd, last version available 6.16 however I noticed when I click at one Power system, and go to CPU or memory, the title of each chart looks weird, like 9۔ַ֖'⇗6vSↆ7Bֶ熀 and should appear as CPU pool : last month
Is there anything I could do to solve this? Other places looks ok