Thanks for setting up the rweek webtags in the compiler. Running the website command showed all running as expected.
I then went back to the CUCharts.def file and added back the weekly rainfall plot and ran the website command, a check of my custom showed that the customlog charts were not running properly. The data for the charts was stored correctly so I reran the extralogs command and the customlogs command. This then produced the full charts in the customlogs area with the weekly rainfall correctly displayed. A minor tweak with the chart names in CUstringsEN.ini and a rerun of the customlogs command sorted the chart line names.
It all looks good to me now.