Well, it would make sense that a font that supports Asian characters would take up more memory than a font that only supports Western languages. There are a lot more glyphs for the system to cache.
And yes, the larger the text and the more characters it has, the more memory the text object will take in memory. Text objects are really 8-bit grayscale bitmaps/textures. Here is how it works. When you create a text object via display.newText() or update an existing text object’s text, Corona must create a new bitmap in RAM, have the operating system draw the text to that bitmap, and then submit that bitmap to the GPU as a texture. The bitmap/texture we create will be set to the pixel width/height needed to fit the text you want, which means larger font sizes and more text means a bigger bitmaps and more memory. This is how it works on all platforms (Android, iOS, Mac, Windows, and WP8). It’s actually an expensive process on all platforms and will have a performance hit if you update text frequently, such on every enterFrame.
For frequently updated text or to reduce memory usage, it is usually best to use a bitmap font library instead. How a bitmap font works is that you’ll have a single image file containing all of the characters needed for your text (ie: a sprite sheet). Only this one bitmap needs to be submitted to the GPU and then the bitmap font library will assembly the character/sprites to form the text you want. This is a very fast and efficient way of doing it and is a commonly used technique by AAA games. However, the bitmap font technique is really only suitable for text that’s under your control because you have to guarantee that all characters you need in your text are contained in your imagesheet. For example, it wouldn’t work well if the text came from the Internet such as Facebook or Twitter because then the odds are high that the characters you scraped from the Internet may not be in your imagesheet.