Language key is entered in SAPscript. Create one SAPscript in Language key German (say, Z_xxx_DE) & one SAPscript in Language key English (say, Z_xxx_EN). Now, go to Payment Method in Company Code (on tcode FBZP) & select the German co code/s with the payment method and assign SAPscript Z_xxx_DE under Form Data. Similarly, go to non-German co code/s with the payment method and assign SAPscript Z_xxx_EN under Form Data.
By doing the above, you can control language to be printed at the company code level.
If you wish to assign different printers for German & Non-German co codes, then you can do so by going into the payment program (such as RFFOUS_C for check payments) and creating individual variants with different printer selections. Further, you can select these variants while doing F110.
Hope this helps.