Is it possible to limit a line to display a fixed number of full-width characters?

I know the CJK version of InDesign has grid-based glyph layout, but it may be only for Japanese. I am not sure if Chinese is supported or can use the character grid.

It's supposed to support Chinese, but in practice, apparently it's not easy. I'm told that it's fairly easy to typeset Chinese with a Japanese UI, assuming you already know Japanese typesetting terminiology, but that the Chinese UI itself has some severe localization problems. That linked article is a better summary of the problems than what I'd be able to write up, but it confirms much that I've been told - that the source of the translation for the Chinese UI was clearly the English translation of the Japanese translation. Also apparently lots of translations get cut off because the menu isn't wide enough, which is (trying not to post like a grown-up, over here, and not fulminate about it) the kind of UI problem that should be caught in a QA check embedded in the localization process. 

So @dublove there are plenty of ways to get the CJK toolset with an English UI, one of which is the Windows registry hack posted over at Ken Lunde's blog. But I think that the fast way to get the layout you are asking for is to place a space after every fullwidth character, including punctuation. Or,.remove all the spaces and use tracking (for EN UI) instead? I found that your ruby/Latin-script transliteration became misaligned if I tried to use Roman tracking, but 1) a space after each bit of punctuation + 2) turning off justification and simply left-aligning the text caused the columns to align:

If you're using a version of InDesign with a CJK toolset, you can control the grid layout directly - at least in the English UI.