Vagonto, for your own sake, I'm just going to say that it's very unlikely that you will link anyone here to any applications they are not already aware of.
Simply put, if you want the music from these games, you're either going to have to spend the time to learn the necessary programming skills yourself or record via line-in, as you said.
As Dais! has pointed out, those tools are known here and have been used. However, they require that the sequences (basically the song data) be in the Sappy format (which is what saptapper also requires). If the games don't work with saptapper, it is likely that they won't work with those tools.
However, if I recall correctly, there are some games that don't work with saptapper, because there is a slight variation in the format/drivers of the GBA ROM that saptapper isn't familiar with. In those instances, those tools you linked might work. Don't get your hopes up though, because even if they do work (which is unlikely), they probably won't work correctly, due to the differences in their format. But, what does it hurt to try?
Really though, you're almost certainly better off with the line-in method. Good luck with that. Mouser X over and out.
However, if I recall correctly, there are some games that don't work with saptapper, because there is a slight variation in the format/drivers of the GBA ROM that saptapper isn't familiar with. In those instances, those tools you linked might work.
The saptapper error message is 'sappy_vsync not found' for those. If sappy_main is missing, game uses a custom driver, and it requires a manual rip.