I would provide some set of accessor functions to, at least, add entities to %ENTITIES. Then, I would submit the patch back to the author along with some tests. Remember - in OSS, if you want something done, the quickest way is to do it yourself. That's why you have the code.
My criteria for good software:
- Does it work?
- Can someone else come in, make a change, and be reasonably certain no bugs were introduced?