Is there a reason this cannot be translated "את רואה אישה יפה" instead?
No. And it can also be "אתם רואים..." and "אתן רואות...". Report it.
I did the same he did and it marked it correct, so definetly fixed :)
atah roeh ishah yafah
יְפֵהפִיָה and יְפֵיפִיָה also means beautiful (as a matter of fact, יפה is more of a pretty then beautiful, while יפהפיה/יפיפיה is beautiful (feminine) and יְפֶהפֶה/יְפֵיפֶה means beautiful (masculine)
I thought that when its talking about a lady everything is in girls form.but then why is יפה not with a ת in it?
Both ה and ת can be feminine endings. In this case יפה is the same for both masculine and feminine.
To elaborate on danny912421’s answer: notice that the pronunciation does shift: instead of yafé for the masculine, you get yafá for the feminine (singular).