Why can には here ONLY mean にとっては?

Question

日本人には________かもしれないが、私たち外国人にとっては、_________はとても大変なことです。

So I answered the first blank with 漢字が簡単に書ける and the second one with 漢字を書くの.

My Japanese teacher, who is a native, told me that it should be 漢字が簡単 because this には functions as にとっては.

She then proceeded to say that the subject of potential verbs would normally be は (if I heard it correctly).

But I have seen countless sentences like 私にはできる and 私には分かる, which both mean the same as 私はできる and 私は分かる respectively (I think). So why is 書ける a big no no in this context? I feel like the second part of the sentence is saying 私たちにはそんなにできない.

I don't think my Japanese is good enough to ask her questions and understand her reply yet.

Answer 1

• 日本人には漢字は簡単に書けるかもしれないが、私たち外国人にとっては、漢字を書くのはとても大変なことです。
• 日本人には漢字は簡単かもしれないが、私たち外国人にとっては、漢字を書くのはとても大変なことです。

First, the particle after the first 漢字 should usually be は (although が is not entirely incorrect), because だが/が/けど/etc does not introduce a subordinate clause, and は after 日本人に is a contrast marker. The topic is 漢字(を書くの) throughout this sentence.

In my opinion, both sentences make perfect sense, but the latter looks a little more concise and natural. This is because there is a clear contrast between 日本人には and 外国人にとっては, and thus it's natural to assume these に and にとって are serving the same function. This way, we have a clean and straightforward contrast, "To Japanese people, kanji may be easy, but to us foreigners, writing kanji is very difficult."

に and にとって are completely interchangeable in this sentence:

• 日本人に(とって)は漢字は簡単かもしれないが、私たち外国人に(とって)は、漢字を書くのはとても大変なことです。