When the boxed set came out recently there were two versions the English and the German editions. I opted for the German edition, purchased of Amazon Germany. I haven't bothered with the English version The musio on both the German and English versions are identical, aside from the lyrics. Which on the German editions is sung in German instead of English. For the box set both German and English versions use the same art work, from memory at the time this was not the case.
All the Kraftwerk Albums were originally recorded in German as intended by the band. The difference being that for the English speaking Market, they decided at the time that their records would probably sell better if all the lyrics were sung in Englsh so they took the original recordings and overdubed the vocals in English. The exception to this rule being the recent 'Minimum-Maximum' DVD,the English Version being entirely different performances and not vocal overdubs.
I haven't and probably won't bother with the English versions. I prefere to own the records as originally intended by Kraftwerk, even if it means I can't often unstand what is being sung. In fact on the whole I prefere the versions sung in German . Autoban for exaple in my opinion sounds better sung in German.
My advice Carlos would be to save up and purchase the German Boxed set,