Hello,
you need to get the properties from this report. It means the name of it, report group. Then you have two transaction to make translation. One is GRRT and second is KETR. Depends of which art of report you have you will take one or another.
There is also another way.
For the elements on the header, it is usually data element and you can info from dd04t table. To translate the lines you can go with transaction SE63, then write TABL and at the end write CEFORMT. In the table CEFORMT are all texts lines from every report painter report. You will get one screen with few fields. One of them is "Report" and you have to write report name in it. Then system will open all text lines from that report.