I found this construction in a couple of places:
Focusing on the third example, the subtitles is "A freedom that I can attain through murder", and automatic translation (which I know can be unrealiable, but in this case confirms the subtitles) is "Freedom that can be gained by killing people".
I know this construction means "even; will go as far as to", and I found this question in which the structure is explained as weighing the worth of actions; trying to read the structure itself, I think it means "Going to the point of doing... to", like "Going to the point of killing people, to be able to get one's freedom".
Using the worth angle from that answer, should I read it as "A freedom that can be attained going as far as killing people", or maybe (with similar meaning, but more stress on worth) "A freedom that is worth killing people to be able to obtain", and the translation given above adapt this in a more natural English wording?
Following this reasoning, the other examples would mean:
母を失ってまでモチベーションが続かない: My motivation can't keep going as far as to take the mother's body (so going on with the motivation isn't worth the death of the mother).
君の歌詞を盗んでまで、彼女が唇の動きを真似るメリットがない: There is no gain in her copying the motion of the lips, to the point of stealing your lyrics (like "What's the point of stealing your lyrics just to lip sync them?"; as context: character A wrote lyrics, character B published video with lip synch - but no audio - of those lyrics without A knowing, and the speaker is speaking about that).
These were from a book, so no subtitles to rely on.
So, can the part with てまで be seen as a (potential) cost to get the following part, like stealing lyrics to lip sync (which seems absurd to the character, hence the negative); and freedom at the cost of killing people?