The only jeopardy for you would be the fact that you don't have enough miles on your account to support 2 seperate award bookings. Other than that, you are totally safe, as it is LH's responsibility to pull the correct amount of miles for a specific type of award.

Btw, who cares about faulty English translation. The German version, and this is the one that counts, is totally clear: "Bei einem Companion Ticket müssen der Senator und die begleitende Person (Companion) stets die Reise gemeinsam absolvieren." Mind the "must" and the "stets", a the latter refers to the requirement that ALL LEGS of the journey must be completed together.