Sticker: 16 Bit Klasse (German)

This could be translated a couple ways - literally "16-bit class" but more likely "16-bit Rules!". Clearly Mattel marketed the superior power and technology of the processor in their system more overtly in Germany. Perhaps they felt that better graphics and sound weren't reasons enough?

Sticker: Intellivision - Das System mit Zukunft (German)

"Intellivision - The System of the Future" might be translated literally as "Intellivision - The System with a Future" - which would be especially ironic. That slogan appears to have been adopted late in 1983, very shortly before the demise of Mattel Electronics. Nice Astrosmash! motif.

Sticker: BurgerTime (German)

I suppose all sorts of bad puns could be made about the name of this game, as "Bürger" is the same as "burgher" in English - meaning a citizen in singular or plural form. There is nothing especially German about this sticker, but that's where I found mine. Clearly, Mattel's one and only true arcade hit needed to be marketed worldwide.

Sticker: River Raid - Jagdflieger (German)

I'm not positive of this, but my guess is that this could be what you got in Germany for joining the 'Activision River Raiders Club' rather than the patch. After all, the artwork is the same as the original version of the patch you got here in the U.S. Although rather than calling you a 'River Raider' you were simply a Jagdflieger - a fighter pilot.