According to the EU norm EN 28601 and ISO 8601 , the first week of a year is the week that contains the first Thursday of the year. It is also (equivalently) the week containing the 4th day of January.
Rainlendar2 supports only Sunday or Monday as first days of week, when counting the number of weeks, according to the the following information from Wiki:
%U Week of year as decimal number, with Sunday as first day of week (00 - 53)
%W Week of year as decimal number, with Monday as first day of week (00 - 53).
This may work in the USA and UK, but not in the EU.
So, we have 27th week now (July 5), Rainlendar2 diplays 26th in the Event List (%W). No setting can change it, including system registry or RL2 settings (different first day of week in the preferences).
Well, question to the developers: Do you consider fixing Ranlednar2, in order to support European week number formats?
Please, add an item to the preferences like "Set week number according to the ISO".