[DNSB]

Originally Posted by Karellen

In your example a simple regex would have fixed that
Find... <span class="text_14">(.*?)</span>
Replace... \1

Then look at what is leftover and figure out what it does and either leave it, replace it or remove it.

Unfortunately, your regex does horrible things if you have nested spans:

<span class="text_14"> blah de blah de blah<span class="text_17">more blah de blah</span>yet more blah de blah</span>

which your regex would convert to:

 blah de blah de blah<span class="text_17">more blah de blah yet more blah de blah</span>

It would be much safer to simply use:

search: <span class="text_14>
replace: <span>

and then remove the naked <span> tags using Diap's "Editing Toolbag" (Calibre) / "TagMechanic" (Sigil).