http://www.hebrewbooks.org/pdfpager.aspx?req=2852&st=&pgnum=174
Look at the second column. This Sefer was printed 6 years after the Maharal was Niftar. This is why I mentioned that perhaps the non-Jews knew about it while we didn’t. We definitely see that the story was around back in the day.
Read the next paragraph for something even more strange, for it seems to be a first hand account of a common phenomenon.
Nitpicker, I don’t either have much invested in the Golem, however I find it silly when people fight tooth and nail that there wasn’t a Golem. Then they say, “Oh, I believe he could have”, while refusing to accept the possibility that he did.
My main reason for accepting it is the tradition, which predates Reb Yidel Rosenberg by many years. He did a great disservice to this tradition by putting out the Niflaos Maharal, although it is possible that he meant no harm, and just wanted to put out a fun book. I once read that he referred to these books as novels. I can’t say the same for the Hagadda, but that’s a different story.