Quick Notice: For many months now I've been struggling with てくる and it's exact meaning when dealing with time flow and indication of change. I do however, understand, when it is used with movement or some action that is coming towards the speaker (I think). I have looked at numerous resources including other posts on here, youtube videos and grammar guides alike.
Anyhow, here I have listed out example sentences with the English translations that were provided:
It's getting cooler.
It's starting to get cooler.
Obviously here the big difference between the translations is that the second translation indicates that the gradual change from hot to cool has just started whereas the first translation doesn't give a time frame for the starting point at all. The first translation sounds like it has been getting cooler for sometime perhaps. I suppose I just don't understand which interpretation is correct or more accurate, or if they are both accurate (somehow)? I also don't understand why both English translations are in the present perfect tense and why this change didn't occur in the past?
The castle is coming into view.
Again with this translation it sounds like maybe the castle has been coming into view for a while. Nothing has indicated that the change has just started. Could it also be interpreted as, "The castle started coming in to view."? Also, again, why is the gradual change here, interpreted to be in an ongoing state and not in the past like the next examples?
I have gotten good at speaking Japanese.
I have gotten used to life in Japan.
The number of people studying Japanese has increased.
In these translations (3-5), the gradual change is indicated to be sometime in the past and it doesn't indicate whether the gradual change is on going or not. In comparison, the first two translations indicate that the gradual change is still ongoing.
How can I tell when てきた is indicating a change from the past 'till the present vs change that is just starting like the first two examples? Also how can I tell if it's something that is still ongoing or if the change is in the past? This has been a total mess in my head for so long now, if anyone could provide me with insight that would be great, thanks!