Thank you for working so consistently on this over several weeks, and for exercising judgement and good taste, and presenting your results so clearly!  Yes, it puts me in exclamatory mode!  

I'll get back to you in email about next steps.  I'm pushing for next week (CPS Spring Break) for doing general version-updates on server blogs2.  The TRA staff will be able to offer keyboard-based hard-labor on Thursday and Friday of that week, so we want to get things in order for that.  We may not get to redistributing the revised/fixed themes collection to existing standalone blogs in that time frame, but at any rate we should immediately revise the files from which new standalone blogs are populated.  

Definitely I agree that Vistared Little and Tiga are worth saving/repairing.  Do you think it might be one of these deals where a theme assumes a plugin ("recent comments") is present and activated?  They're supposed to code a conditional around a fragment using a function introduced in a plugin, but maybe we have these themes in versions antedating that standard.  [Which would mean it's worth checking the versions on themes, something I've been avoiding thinking about.]

Good job and thanks again!