However, ithe store was closed that day. However, the store was closed that day.

This one is a little nitpicky, but "greengrocer" can be both the store itself, or the owner of the store, so it ends up sounding a little weird to say "it" to refer back to it because of that ambiguity. The same is true for a lot of similar words like "fishmonger", "butcher" etc. Also all of these words sort of imply a small store when used alone to describe a store.

As I meandeared, I noticed a wonderful aroma swirling around me. As I meandered, I noticed a wonderful aroma swirling around me.

"Swirling" isn't wrong but "wafting" is often used in relation to scents so would be a good word to use here.

As I meandeared, I noticed a wonderful aroma swirling around me. As I meandered, I noticed a wonderful aroma swirling around me.

As I meandeared around, I noticed a wonderful aroma swirling around me. As I meandered around, I noticed a wonderful aroma swirling around me.

It seemed to be coming from a confectionery shop right in front of me. It seemed to be coming from a confectionery shop right in front of me.

This is correct, but you could also use "the* confectionery shop right in front of me", since it is the only one in front of you. If it wasn't the only one, then you would instead use "from one of the confectionery shops in front of me." Also, in American English, we would use "candy" instead of "confectionery" (which is more of a British English term, and maybe Australian?). If you care about that distinction.

"I wondered, H "Was this shop been here before? ". I wondered "Was this shop here before?".

Simple past tense is best here. Speech marks should only go around the part quoted. Unless you thought or said "I wondered", those should not be in the speech marks.

"I wondered, H"has this shop been here before? " I wondered, "has this shop been here before? "

Since "has this shop been here before? " is the thing you wondered (and not the "I wondered" part), that is the only thing that should be in quotes.

"I wondered, Hwas this shop been here before? " "I wonder, was this shop here before? "

Drawn in by the aroma, I stepped inside. Drawn in by the aroma, I stepped inside.

Alternate suggestion: "Drawn to the aroma, I stepped inside."

I bought some to try and ended up eating them in the car as I drove. I bought some to try and ended up eating them in the car as I drove.

So there's nothing wrong speaking grammatically here, but this sentence and the follow-up did confuse me because it seemed like you were buying sansho peppers rather than a sweet made with the peppers. I might suggest adding a sentence before this explaining that there were confections made using sansho, or adding that information to the previous sentence.

The confection was made simply with flour, sugar, and eggs, and flavored with sansho, giving it a peculiar taste. The confection was made simply with flour, sugar, and eggs, and flavored with sansho, giving it a peculiar taste.

See the above comment.

The confection was made simply with flour, sugar, and eggs, and flavored with sansho, giving it a peculiar taste. The confection was made simply with flour, sugar, eggs, and flavored with sansho, giving it a peculiar taste.

If I understood your Japanese post correctly, I would probably use "particular" instead of "peculiar," since "peculiar" means strange/unusual, which tends to have a slightly negative connotation (without explicitly stating that it was a positive experience), whereas "particular" just means unique/unlike other things (and has a neutral connotation). Separately, If you wanted to make the distinction/subtlety that the 山椒 flavoring/aroma should be interpreted as somewhat separate from the other 3 ingredients, then you could instead say: "The confection was made simply with flour, sugar, and eggs, then it was flavored with sansho, giving it a particular taste."