I like to edit many of the movies I own for personal use. Usually, it is to cut out language that I deem inappropriate for my family.

I have been using SolveigMM video splitter to cut (or mute) the scenes I don't want. However, that doesn't always work (with PCM files for instance, the mute function isn't working)

Since I decide which words to cut by looking at the subtitle file, I know which timecodes I want muted. That leads me to three different options (for audio) that I'd like help with (Note that I want to avoid any kind of transcoding of the video)

1. THIS ONE IS MY PREFERENCE: Can I just use audacity, silence the vocals of the scene I want to eliminate language from, export as AAC (or AC3? or FLAC), keep it in surround sound (will that work?) and remux with the original video using mkvtoolnix? I'm getting errors when I try to export as AAC, (it's a 7.1 audio file and this is the error code I'm getting [invalid parameter 0x15002]. How do I export an aac file that is 7.1 in 7.1 using audacity? It only lets me do FLAC in 7.1, unless I use command line ffmpeg and I have no idea how to do that.

2. I've seen a lot of people use ffmpeg to do something similar...using command line like this:
ffmpeg -i in.mp4 -af "volume=enable='between(t,3.200,3.500)':volume=0,v olume=enable='between(t,7.5,8)':volume=0" -c:v copy out.mp4

3. Is there a lossless audio editor (similar to SolveigMM or TMPGenc) that I could use for just the audio so I could remux that audio back into the original video file?

Is there a gui that would let me put in the time stamps so I don't have to do all of this via command line? I can easily get the time stamps via the subtitle file.