Yes. We’ve learned first how to do it correctly, grammatically, and by seeing the words. It must works differently when you learn by hearing.
Genders are so confusing. I guess you simply have to learn them by rote. My native language has genders, too, and it tends to sound quite off when a non-native speaker gets them wrong. I guess it must feel like that to a German or French person when I try to speak to them in those languages.
OK, I’ll bite. Don’t you mean “muster?” Passing mustard sounds uncomfortable.
Another one with vague forgotten military origins is “toe the line,” which loses (OK, looses) all of its evocative power when written as “tow the line.”
And once I saw “waifer thin,” which pleased me greatly.
Since we’re not just talking about homonyms any more, I regret to report that improper usage of “momentarily” will soon become customary and standard. I hear too many supposedly smart people and coporations using it.
“Our next customer service rep will be with you momentarily.”
Swish!
Dang!
I’ll take this one up!
In many parts of the UK it’s pronounced lack-s-adaisical. There’s an s in there so it makes perfect sense for people to spell it with an x. It also links back to ‘lax’ which has a related meaning.
For my own one: Peaked/piqued.
Can’t tell you how many guys who have emailed me and failed to ‘peak’ my interest due to them using the wrong word. 
If you think that’s bad, wait till you find a society where homonyms are not only useful, they’re the basis for humor. (Anyone from Osaka?)
That’s just a few moment of choral homophony.