Point of view in Japanese writing, verb tenses and temporal location?


A little while ago, I asked this question about the Japanese point of view:
[How do you identify the point of view in Japanese (for
novels)?](https://japanese.stackexchange.com/questions/87272/how-do-you-
identify-the-point-of-view-in-japanese-for-novels) The answer seemed to be
that you need to watch for the pronouns, when there is some. I realised that
there's more to it than just identifying if it's first or third person. Take
this example from 浦島太郎 (Urashima Tarou), a known Japanese fairytale:

> 昔、ある所に、親切な漁師がいました。名前は、浦島太郎です。ある日、子供が六人ぐらい集まって、浜辺で亀をいじめていました。

So far everything seems fine, this is the beginning of the story and an
English speaker would think it translates to something like: "A long time ago,
there was a very kind fisher. His name (was) Tarou Urashima. One day, around 6
kids gathered and bullied a turtle on the beach." The issue arises when later,
this sentence is used:

> [...] 太郎は自分を呼ぶ声を聞きました。「太郎さん、太郎さん」 **見ると、船の近くで亀が泳いでいます。**

This is very striking for an English speaker: "Tarou heard a voice calling
him: "Tarou, Tarou". Next to the boat, a turtle **is swimming**." At first, I
thought it was first person being suddenly used. But I kept the perspective of
@aguijonazo in mind (from the other question): "Generally, I wouldn’t say it’s
common to switch perspectives in one novel. I would think a work that freely
switches between first-person and third-person modes would be considered a
poor piece of writing." So then, if this isn't first person, this means that
the third person narrator went from speaking of something in the past to being
in the scene with 太郎さん. **The narrator literally jumped in time.**

These are my questions (from a Japanese perspective, not subjectively): Can
the narrator jump in time whenever he wants in Japanese? Is this considered a
poor piece of writing or very natural? An english speaker would expect
泳いでいました, would this also feel natural to use?

