Terrible Accuracy?

I wonder why the pre-trained model with the lm.binary + trie they provide return such inaccurate results. If I create my own lm.binary with just a handful of words or sentences it works wonderful (like here), but just for these sentences/words. If I replace that LM with the one they provide, the results make no sense again. (words make sence but not in relation to each other even tho lm&trie provided)

I wonder If accuracy would improve with a acoustic-model trained with the CommonVoice Dataset + different Language-Model. Does something like this already exist OpenSouce?

Or am I missing something and this should work fine?