My opinion only here - I think it is hard to list all the LEs in a timely fashion because:
Locale, Platform & Function -many of these special editions are limited to a top authorized dealer, or a country/city, or a specific boutique. Rightly, or wrongly, these editions are 'special' and geared towards that purpose - disseminating information widely about it defeats the purpose. For instance the 2012 Portuguese Automatic 5001 'Dragon' Edition was announced only in the Simplified & Traditional Chinese editions of Watch International - all other versions omitted it, because it was targeted towards that market / those cities' boutiques. Of late, as we have seen in the posts, this piece can be picked up elsewhere in other cities' boutiques (I think other boutiques have the ability, subject to supply, to 'order in' a few pieces if they choose).
Timing - different special editions are released at different times, and I think kept 'secret' until then (or else it would be less special ?) Any 'list' would be have to be constantly updated and broadcasted and edited, and laid out nicely, for the purpose of a media broadcast, which involves time & moeny, and I am guessing this will only happen if the need for it is very high. My personal opinion is that the need is not great - as recounted here.
Co-ordination & Production practicalities- I am also guessing that production numbers must reach (or anticipated to reach) a certain number before it can be feasibly be announced - and this is in turn is contingent on production capability (including passing quality controls (especially for an out-sourced, sub-contracted part), or mere production time which could be influenced by the priority of the piece). In my dialogues with HK Flagship Boutique about their recently-announced special edition, I am made aware that one issue for instance was that of design, so time I suppose is needed before a decision is made - and there will be an element of uncertainty in the timing.
Ownership & Responsibility of broadcast - if it is an authorized dealer special edition, I am guessing the onus lays on that AD to do the necessary marketing & publicity so as to sell that piece... and that in turns is contingent on the marketing & publicity ability of that AD.
Language - special editions in non-English languages do not reach the English-speaking sphere as fast as it does others. And by then, many may have been sold that marketing is no longer needed by the responsible point-of-sales boutique/dealer.
Sales- some special editions are sold off so quickly that the general community knows only through forums such as ours' or when it is re-sold.
I think in january this year @ the Collectors Dinner this question was raised again, and if I recall correctly the answer was that that task would be difficult. I am guessing with what I have written above that these would be some of the issues involved - corrections welcome.
My personal opinion is that keeping track of such things can well fall within the co-operative domain of communities like this, like ours. And... there are also always nice surprises - a steel Portuguese Perpetual Calendar ? A 'Taiwan' Portuguese Automatic ? the list goes on...