I noticed that there's an english_dialogue tag, but instead of just editing it myself I figured it may be better to simply have it aliased to English_Text since it's a perfectly acceptable way of saying the same thing but against the standards already set at e621.
I checked the Aliases and Implications and there don't seem to be any relevant ones in place.
http://e621.net/tag?name=*english*&type=&order=date&commit=Search
Other variations currently in use are
english_texts
englishtext
Updated