Although copying and pasting accented characters has been a feature since early versions, the Ŵ ŵ Ŷ & ŷ characters used in Welsh are not available in any character set.
Ideally UNICODE is required but UNICODE is not supported by the programming language in which Simply Calenders is written.
Fortunately, there is a special Welsh font which contains these characters:
Pryd Euro-Cymraeg .
If you download and install this font it can be selected and used by Simply Calenders.
The characters Ŵ ŵ Ŷ & ŷ will be found in the Find Character table when this font is selected.