Intentionally annoying people when not necessary in the hope that they do something good is not a tactic that we encourage in MediaWiki.
Fulup and I have been translating a main part of what you can find in Breton here. We know Breton wiki for years, and we know how it works as we are part of it, so could you please listen to our answers to your proposition ?
I'm grateful for your translations, hence I'm listening and I'm seriously considering all your arguments. I heard contradictory arguments about what annoys people more, an English or a French string, and whether such annoyance brings people to translate more; my answer is simply that, whoever is right, this argument is unacceptable.
"What worked so far" is also not an acceptable argument, because it's based on a biased sample (those who could live with the [almost certainly] sub-optimal configuration this language had, differently from all the others).
Back to concrete proposals: if you need ways to find out that some new messages urgently need to be translated, that's a very important issue and we need to work on a feature in Translate that fixes it systematically. The current system only provides two ways: using Special:LanguageStats to translate certain important groups completely; and visiting Special:Translate/!additions regularly to see new messages. You're saying you'd need something else or something smarter, correct? What kind of system would you like to have and how often would you like to check (or be notified)?
Thank you for listening and considering all our arguments. I have a question for you. How is it that French citizens, knowing perfectly French and having an excellent French language wiki at their disposal choose for some of them to give thousand of hours of their time to translate strings or write articles for a tool they perfectly know could never ever compete with the French one. And why is it that some others prefer to read best bad Breton articles than consulting directly a good one writen in French? This is one thing. Secondly, you talk about improving the way of finding messages to translate. Seems a good idea to me although I do appreciate already Translatewiki since years because I was already here working for Breton when it was called Nukawiki. So I value all the impovement that have been made since the beginnig. The thing is it is still very uneasy to find a particular string because one can't make a globabl search. You have to know in what section the string is. So one has to search in wiki strings, and then in wiki extensions, and so on. Although, it is not possible to search from a part of a word only, which is very bad in particular for Celtic languages where the first consonnant of a word change depending on grammar. For example if I want to search the word kemennadenn, I have to search it three times, I need to get kemennadenn, gemennadenn, c'hemennadenn and this in every possible section. This is time consuming. And of course, the big news is that now we have French language in our wiki where it used to be English. So now it is just impossible for translators like me to find the string we want to translate because we see a French string on our wiki and we don't have a clue of what is it we have to search in English because we don't have access to the original string anymore. May be you can understand, this is not what I call an improvement for the Breton wiki. And last but not least it would be very nice, in order to homogenize terminology more efficiently if it were possible to replace one specific word in a more systematic way, a bit like the search & replace function in Word.