To maintain your desired Date Formatting when concatenating dates, remember to enclose each date with TEXT() eg CONCATENATE(TEXT([DateCol1]), “and”,TEXT([DateCol2]))
TEXT([REPORT ID], " DDDD, DD MMM YYYY") as expression for the Day column?
Edit: However this works only for the virtual column. Real columns seem to convert it to number as you have mentioned.
Edit 2: In case of real column,please change the back end column type for [Day] to “Plain Text”, if you are using Google sheet or suitably to similar column type “text” with other spreadsheet or database. With this setting of even the real column will show the date in the format you desire.
So even without trying anything else, as I suggested in my post earlier, you may first try simply changing the back end column type to “plain text”