Grew up with immigrant parents where Mandarin was spoken in the household but lived in a area with no other Chinese-Americans. Even though I was exposed to the spoken language daily, I wound up forgetting how to read and write Mandarin by middle school.
Did my best to re-learn it but I rarely ever read/write in Mandarin so I would just regress after a bit - by this point I think I’ve re-learned how to read or write basic Mandarin at least three times and have regressed each successive time. Interesting note is that I seem to be significantly faster at re-learning things each time I go back to it, but that might just be constant repetition more than anything.
This is the phenomenon exploited by spaced repetition learning. “Trying to remember” is when you learn things the best.
Reading something in Mandarin for a couple of minutes every few days will be better than weeks of effort every few years, even though it's less time spent overall.
And I can't communicate verbally at all...
That said, the voice in my head just pronounces the Japanese Kanji in my native Cantonese...
I doubt anyone _actually_ learns Mandarin without learning how the common characters are pronounced... Unless you don't have to verbally communicate with a teacher / fellow classmates?
When I go through a text I understand I either don't sound the words or pronounce broken translation in my mind.
I've doubted this approach a few times because, as you say, it's uncommon, but I'm sticking with it and I'm curious what comes out of it in a year or two.
For instance, rewriting your sentence above into something somewhat like this:
I finish wonder this; accept word element character language, you not think word ability read language.
Hardly readable once you start getting long sentences in books. Japanese speakers can't just natively go ahead read and understand 95% of a Mandarin book even if they know all the Simplified/Traditional Chinese characters which are not commonly used in Japanese. They can sometimes understand simple sentences, and can more easily understand, say, street signs.