what is the indication that this is past tense? Shouldn't 'he manages to change' be acceptable?
Past tense doesn't exist, it's all context. But yes, your answer should be accepted as correct.
I think "He/she succeeds/succeeded in changing" should also be accepted. It means the same thing.
I wrote "He succeeds to change" and it said wrong, the correct one is "He succeeded to change".... WHY??? Nothing indicates it's something in the past!
"Succeed to do..." sounds odd to my ears. I would say "succeed in doing..."; but it might be a regional thing.
In the sentence "He manages change" change is a noun.
Another way to put it in English is "He manages the changes"
"He manages change" would be "Dia berhasil ubah" I believe.
"berubah" means "to change" it's a verb. It's the act of changing.
For example "He changed into a dog" would be "Dia berubah ke anjing" I believe.
I say I believe because I'm not a native speaker.