Thank you for the feedback.
A possible change of this filter might be quite crucial to many other clients. I can understand that to change span tags to font seems awkward and somehow incorrect. Although, you should note that the RadEditor is commonly used for emails' body creation, and thus, used in many legacy systems that entirely depends on how the HTML is rendered.
When it comes to such matters, we cannot just redesign a filter that is commonly used and disregard the fact that many other developers of such applications will struggle on investigating what possible went wrong and why something previously working, do not work due to a minor change of a simple built-in filter.
As for the case, as you can see the mentioned filter can be easily modified to perform as per to your requirements. And a possible, even more reliable option is to disable it entirely and build a custom filter
that suits best the encountered case scenario.
On a side note, when it comes to logging a feature request, you can always directly log one in our Public Feedback Portal
and place the desired description, so that other developers in the Telerik community could vote for it.
Let me know if I can help any further on the matter.
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