Regex for flipping year month to month year

I have a field Filename where the naming convention is usually 2025 May Report.xlsx or 2025 January Report.xlsx

I have used the filenamepart extractor transformer to fetch the filename along with a string searcher transformer just to extract the year and month  from the filename. 

Now I want to create an additional field where I can flip the year and month -→ Month Year. How can i build the regex to achieve this? 

Also I might be expecting different scenarios where January is written as Jan, JAN or january