Hey Michael,
I’m going to second Gabe’s recommendation.
Typinator is going to be faster and easier to use than a Keyboard Maestro solution for many hundreds or thousands of text expansions.
If you really want to explore a Keyboard Maestro solution Dan Thomas posted an excellent Keyboard Maestro Custom HTML Prompt example: Spotlight Search Prompt
I have a test case that uses a 10,000 line text file for input, and it’s pretty fast.
-Chris