Thanks for the positive review, I also feel they are useful.
I do not disagree with your criticisms of the first three examples, though there was an implicit assumption in the offered correction that the error should be more properly considered an independent clause of either the preceding or following sentence. I stated this explicitly with the correction for “That bill died in committee.” As you pointed out, it may be more a question of style, but I think the corrected passages read a lot easier.
The biggest problem is: It is difficult to pin down the exact nature of the error. The rule only says that an error of some kind is highly likely. The other conjunction rules I am working on have a similar problem; they catch errors, but where and why can be very difficult to explain. Often, the errors are more to do with lousy sentence construction than anything else.
I have been sweating blood trying to succinctly reflect this in the error messages. By the way, you do realise, to make navigating the error report easier, I cut out the bulk of the message. In retrospect this was probably a mistake, (it made sense at the time). The full error message, as reported above, is currently:
R0.1B: This can be a subtle error: “\2 \3” introduce a subordinate clause; however, there is neither punctuation nor coordinating conjunction to indicate a main clause. Alternatively, if the SC is subordinate to the preceding sentence, the two sentences should be joined. A subordinate conjunction ending a sentence would normally not be punctuated: Though a colon may be used for emphasis. Another possibility, with narrative or rhetorical styles, is a missing question or exclamation mark. Finally, correct punctuation is very sensitive to phrasing.I would be grateful for feedback on how I can improve this.
Irvine