Why the stream uses the British E-boat label

Why call the craft E-boats when the Germans called them Schnellboote?

Because the stream follows the British wartime perspective, in which E-boat was the Allied label commonly applied to the German Channel threat.

The E-boat label follows the way British forces described and countered the threat. S-boat could be ambiguous in British discussion because it might also suggest submarines, whereas E-boat marked an enemy small craft. In Channel usage the term often pointed especially toward the large Schnellboote. The distinction explains the British source perspective without claiming that E-boat was the German designation.