Hmm, I understand Vことになる vs Vようになる not the same way as you explained. I change example sentence a bit.
[assume that you go to XXX country every week (do it as a manner)]
Event 1: 日本に行くことになる means that: Certain occurrence will be changed to Japan, but you still have to go to XXX country in other occurrences
Event2: 日本に行くようになる means that: From now on you will have to go to Japan instead of XXX country (becoming manner of going to Japan)
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Hmm, I understand Vことになる vs
Hmm, I understand Vことになる vs Vようになる not the same way as you explained. I change example sentence a bit.
[assume that you go to XXX country every week (do it as a manner)]
Event 1:
日本に行くことになる means that: Certain occurrence will be changed to Japan, but you still have to go to XXX country in other occurrences
Event2:
日本に行くようになる means that: From now on you will have to go to Japan instead of XXX country (becoming manner of going to Japan)