Finally, Shanghai welcomed this autumn, aautumn has arrived in Shanghai. And, my favorite flower in Autumn, osmanthus, has been blooming. Finally, autumn has arrived in Shanghai. And, my favorite flower in Autumn, osmanthus, has been blooming.

"Shanghai welcomed this autumn" is perfectly fine grammatically but doesn't sound natural.

Finally,At last! Shanghai welcomed thise autumn, and my favorite flower in Autumn, osmanthus has been blooming season, which also brought in the blossoming of my favorite flower—the osmanthus. At last! Shanghai welcomed the autumn season, which also brought in the blossoming of my favorite flower—the osmanthus.

Finally, Shanghai welcomed this autumn, and my favorite flower in AutumnAutumn flower, osmanthus, has been blooming. Finally, Shanghai welcomed this autumn, and my favorite Autumn flower, osmanthus, has been blooming.

It sounds better to say Autumn flower. Also because osmanthus is a bit of extra information, we need a comma on both sides. As a side note, you use the american spelling of "favorite", but you're using "autumn" instead of "fall". I haven't corrected it, but it's something to think about~

I can smell it when I open my window in the morning, and when I walk on the road. I can smell it when I open my window in the morning and when I walk on the road.

I can smell its fragrance flow in when I open mythe window in the mornings, and when I walk on theor (surrounds me) when I'm simply walking down a road. I smell its fragrance flow in when I open the window in the mornings, or (surrounds me) when I'm simply walking down a road.

I can smell it when I open my window in the morning, and when I'm walking on the road. I can smell it when I open my window in the morning, and when I'm walking on the road.

Using present continuous is what i would say if i was speaking.

I so love the sweet and joyblissful fragrance of osmanthus.es, I so love the sweet and blissful fragrance of osmanthuses,

I love the sweet and joyful fragrance of osmanthus. I love the sweet and joyful fragrance of osmanthus.

It's not necessarily wrong to use joyful, but it also doesn't sound particularly native in this context. Maybe something like "sparkling" would get the same idea across, and as a bonus it alliterates

I often bought someso much that I often buy perfume thats claimed to smell like osmanthusing its wonderful fragrance. so much that I often buy perfumes claiming its wonderful fragrance.

In the past, I often bought some perfumes that claimed to smell like osmanthus. In the past, I often bought perfumes that claimed to smell like osmanthus.

"often" implies more than one time, so making perfume plural works better. You could also say "bottles of perfume". Using "some" without making perfume plural or specifying bottles makes it sound like you are talking about the liquid contents of a particular brand that you bought multiple times. From the next sentence, i assume this isn't your meaning.

But unfortunately, somehow they were not somehow,n't reminiscent of osmanthus' fragrance. This happened with even those I thought it wasried for the first time. But unfortunately, somehow they weren't reminiscent of osmanthus' fragrance. This happened with even those I tried for the first time.

I'm not 100% sure what you mean by "even those I thought it was the first time" so my replacement sentence is my best guess. I extended on your original work to add clarification so that the reader can follow more easily. Putting somehow upfront improves sentence flow.

But unfortunately, they were not somehow, even those I thought it was theto my disappointment, they weren't (though I really thought they were at first time). But to my disappointment, they weren't (though I really thought they were at first).

But unfortunately, they were not somehow, somehow they did not, not even those that I thought it was the first timat first were accurate. But unfortunately somehow they did not, not even those that I thought at first were accurate.

Anyways, I really enjoy these autumn days. Anyways, I really enjoy autumn days.

Perfectly find grammatically using "these autumn days" but simply "autumn days" sounds more natural.

AnywayNevertheless, I reastilly enjoy these autumn days. Nevertheless, I still enjoy these autumn days.