Using the word Blitzkrieg casually in German is no more acceptable than trivialising the Holocaust by using literal translations of horrible words such as grammar nazi. In each case one would need to find a suitable translation, far removed from any nazi-specific imagery. Violent imagery in general, even war imagery, is no problem even if the word Blitz (flash) is included.
PS: It now seems to me that more precision is in order.
In Germany there is a general taboo around most words that are specifically related to the nazi era. It is no problem to use words falling under this taboo in their original sense, but casual figurative use is considered inappropriate. Both Blitzkrieg and Nazi fall under this general taboo.
This taboo is strongest for words with direct connection to the Holocaust (e.g. KZ, i.e. concentration camp), somewhat weaker for words that can be seen to represent the entire period in all its facets (Nazi falls in this category), even weaker for words that relate specifically to war as opposed to (other) crimes against humanity (Blitzkrieg falls in this category), and weakest for words that relate to other phenomena related to the era but not directly to war or crimes (e.g. Hitlerjugend, i.e. Hitler Youth).
Sometimes the status of a word isn't so clear. E.g. Endlösung (final solution) has been a normal German word long before the nazis applied it to the 'Jewish question'. As a result, the word is treated as totally harmless in some contexts, but falls under the strictest form of the taboo in others.
If you were to say Grammatiknazi in German, this would in principle fall under the taboo against trivialising figurative meanings, but a lot of people would also understand that this is an anglicism, so it is not clear to what extent the taboo applies. However, Blitzkrieg is the original, unchanged word. Therefore, even though the original taboo is somewhat weaker for Blitzkrieg, the overall effect is about the same for both words.
It is also important to understand that this taboo is strongly associated with the admission that the Nazi crimes were wrong and in some sense unprecedented, that Germany lost the war, and that none of this should ever be repeated. In the German context, for a long time not abiding by the taboo has meant that you wanted to revisit these issues. Just like saying "Not everything was bad about the Nazis", ignoring the taboo is not objectively wrong per se but only through the fact that it is aberrant behaviour that signals disagreement with the general consensus of society concerning the period.
The lapse of time has been weakening both the consensus and the taboo. Nowadays a lot of Germans spend a large part of their time in the English-speaking parts of the internet. Consequently, English coinages such as grammar nazi and the figurative use of blitzkrieg contribute to the gradual loss of the taboo in much the same way that the realisation how normal and main-stream racism and extreme nationalism are in countries such as the US (Trump), France (Front National) or Hungary contributes to more open extreme nationalism in Germany.
As a result, yes, you can get away with using the word Blitzkrieg in a translation in this way. But you can neither use it nor avoid it without taking a position.