"We wrote four letters on Wednesday."
Translation:Ve středu jsme napsali čtyři dopisy.
The auxiliary forms of být -- JSME in this sentence -- are among the words that want to appear in the "second position" in the sentence or clause. This is not always after the first word -- in this sentence, for example, JSME follows the first "unit of meaning," which is VE STŘEDU. You'll have plenty of exposure to the "second position rule" as you work through the course. This can be pretty confusing initially... but it does get better if you stick with it. :-)
It would not emphasize the four letters but the writing. It would correspond either to "We did write four letters on Wednesday." (contradicting someone's claim that we did not write four letters on Wednesday) or to "We wrote four letters on Wednesday." (correcting someone's statement that we read four letters on Wednesday). I am on the fence about accepting it. Either way you are getting into the weeds of the Czech word order here that you may not be equipped for, and I am not sure whether you learn more from rejection or from acceptance.
Thanks for your reply. I was just curious because so far my gut feeling (and the "Another Translation Bubble") always rather had the past participle than the object at the end of the sentence... so I thought that that's the way to go if you don't want to emphasize anything. ;)