In short, yes, the alert settings in the skin are "correct", and it's not a Weather.com bug. Take a look at this (I replicated your approximate location around Valencia, Spain): You can see the skin at the top right corner, the skin code from the file at the top and the Rainmeter log at the bottom of the image. The measure that "extracts" the alert from Weather.com exists and works out fine as you can see in the log (i.e. @Alert1Text, @Alert2Text and so on), it's just that the skin intentionally doesn't display "minor" alerts like these, aka alerts having a of 4, as you can see by reading the line I selected from the skin code comments.
Bottom line is, while these minor alerts aren't normally being displayed in the skin, you can easily add them by either adjusting the / options from the [MeasureAlerts] measure accordingly (basically just make the option that corresponds to the severity code of 4 to look like the similar options that show meters at severity codes less than 4), or just make some meter of your own and use or something along these lines to display those alerts as well in other places of the skin.
Even more to the point, all you have to do is comment (add a at the start of the line) the line and uncomment (remove the at the start of the line) the line - these lines and the measure containing them are visible in the image that I attached above, by the way.