What is the difference when I swap が and は in this sentence


I want to know if my first translation of a sentence is wrong and more
importantly **why**.

I'm using Duolingo as one of a couple tools for learning Japanese. Today I got
the sentence "The coffee here is delicious" At first I translated it "ここ **が**
コーヒー **は** 美味しいです" In my head the super literal translation came out to "here
**is the target location of** coffee **that is** delicious." Duolingo said it
was wrong and that my が and は we're backwards.

I now know **は** marks the topic of the sentence and **が** marks the subject
of the verb.

So the translation I gave I think is closer to "In reference to the coffee,
here it's delicious"

Am I still interpreting the Japanese I wrote wrong? Is this bad grammar or
just weird sentence structure?




ここがコーヒーは美味しいです is a perfectly correct sentence, but it's nuanced. This is a
correct sentence if you wanted to say " _ **Here**_ is the place where coffee
is delicious" or "It is _**this**_ shop that offers delicious coffee". A
sentence like this is natural only when someone asked you about the best café
in the town or asked you to guide them there. This type of が is called
exhaustive-listing が, which is a particle used to say "(this is) _the one_ ".

  * [Why is this sentence ungrammatical? 「お寺が公園のとなりです。」](https://japanese.stackexchange.com/q/68923/5010)

However, for now, you have to translate "The coffee here is delicious", which
is a plain sentence that does not emphasize the "here" part. You have to
translate it plainly without emphasizing "here". A natural way of doing so in
Japanese is to construct a so-called "double-subject" sentence. You can mark
ここ with は, making it as the topic ("Here, ..."), and then say コーヒーが美味しい
("coffee is delicious"). I think you have seen typical double-subject
sentences like 私は猫が好きです ("I like cats"), 彼は背が高いです ("He is tall") or ゾウは鼻が長いです
("Elephants have a long nose"). You need to follow the same pattern here.




ここがコーヒーは美味しいです is a perfectly correct sentence, but it's nuanced. This is a
correct sentence if you wanted to say " _ **Here**_ is the place where coffee
is delicious" or "It is _**this**_ shop that offers delicious coffee". A
sentence like this is natural only when someone asked you about the best café
in the town or asked you to guide them there. This type of が is called
exhaustive-listing が, which is a particle used to say "(this is) _the one_ ".

  * [Why is this sentence ungrammatical? 「お寺が公園のとなりです。」](https://japanese.stackexchange.com/q/68923/5010)

However, for now, you have to translate "The coffee here is delicious", which
is a plain sentence that does not emphasize the "here" part. You have to
translate it plainly without emphasizing "here". A natural way of doing so in
Japanese is to construct a so-called "double-subject" sentence. You can mark
ここ with は, making it as the topic ("Here, ..."), and then say コーヒーが美味しい
("coffee is delicious"). I think you have seen typical double-subject
sentences like 私は猫が好きです ("I like cats"), 彼は背が高いです ("He is tall") or ゾウは鼻が長いです
("Elephants have a long nose"). You need to follow the same pattern here.

