I also though about that, but the above ones are just simple examples. Adding some 5-10% to the existing sentences would be more than enough and I think it will not be boring. If I only knew the actual amount 
I see that we have new sentences to be recorded, probably from Wikipedia. There a quite a few technical sentences such as polimer structures or domain names (domain dot com) etc, also with many words/places from English and other languages. I think we need to balance these…
Any alternative method / suggestion is also welcome.