Fire it up outside the lantern, and see how hot it gets. Pay attention to what part of the lamp emits the heat, and fashion a shield of aluminum behind/below/above that part. I doubt if a 10W lamp will give off too much heat.

Not possible to 'fire' it up yet as I was considering returning it, so I don't have it connected to a transformer to try this out or I would have. Want to solve the possible heat issue first. Don, won't aluminum get hot also? Thanks for your reply

A piece of aluminum sheet, placed between the lantern surface and the hottest part of the lamp will act as a heat sink, and insulate, to an extent, the lantern. If the heat is produced at the lens of the lamp, that will, of course block some of the light.

Just want to let you all know that I did buy a low watt transformer with timer for the above light in question-my DH wired the 2 together and I now have a nice little light in my Japanese lantern. At this point I have it lite up in the basement, checking every so often for heat above and below, and I'm very pleased with the results, no heating up of the 'roof' (this was my main concern) and very, very little on the platform below on which it is placed. I'm very pleased with this light, although this is an expensive set-up, but after all the lantern it self only cost pennies to make! The blood sweat and tears in the labor don't count anymore!
Thank you Don for your assistance, and yes I wouldn't want little hands reaching inside and touching the light it self, it does get very hot! I just had to try...ouch!

The thank-you is intended for donn. My apologizes. Wendy