number is not right. You have left too much of the one from the Wiki, so it allows commas every three characters. You want
Context()->{pattern}{number} = '(?:\d+(?:[.,]\d*)?|[.,]\d+)(?:E[-+]?\d+)?';
Note that this does allow ,123 as a means of entering 0.123, which looks strange to my eye. I don't know if that is the usual notation or not. If you want to force a zero before the comma, use
Context()->{pattern}{number} = '\d+(?:[.,]\d*)?(?:E[-+]?\d+)?';
Context()->{pattern}{signedNumber} = '[-+]\d+(?:[.,]\d*)?(?:E[-+]?\d+)?';
The second issue has to do with the text of the problem, not the answer checking. In TeX, the comma is formatted with a little space after it (it has the TeX class of punctuation, and the extra space makes things like vectors format better). When used as a decimal indicator, it should not have that space. To avoid that, use braces around the comma. So the statement of the problem should be
BEGIN_TEXT
Enter \( 3.14 \) or \( 3{,}14 \): \{ ans_rule(10) \}
END_TEXT
This is a TeX subtlety that is easily missed, but if you look at the spacing for these, you will see a difference.