In my experience, when in the 〜て＋くる form, it is more often written as Hiragana as opposed to Kanji. However, I don't think there is any major nuance difference.

In the case when there is nothing actually physically arriving, like "わかってきた”　or "頑張ってきた”, I feel like it is even more common to use Hiragana over Kanji.

Personally, I always use Hiragana with the 〜て＋くる form.

Of course, if the verb was used by itself, I think it would be more natural to use Kanji (i.e. 友達が来たよ), though you could still write it either way.

I think the usage of whether Kanji is used is a very subtle matter, and the author's choice of which to use can be related to the tone they want to impart, and their target audience. Using Kanji generally feels more 'formal' to me.