I've already been using the one in French version.

"the one in French" or "the French version"

Recently I’ve got a Greek version.

Recently, Iit finally got oncame, because the authentic company in Germany had refused to accept my order then.

It was not that there wereas no stock, so I was not sure why.

IThat was last January, so it took so much a long time to be delivered to me.

'such a long time' sounds a bit better

I know that purchase overseas is not so smoothly to be doneoverseas purchases don't go as smoothly, especially aboutregarding shipping time.

When I ordered a German book via Amazon.UK before, I received it within a week.

UK before, I received it within a week.

Purchase overseasOverseas Purchase

Its unique typography-likeic display with glowing letters has earned a goodspecial reputation not only as a clock but also as a modern art.

"good" feels very flat/underwhelming.

"as modern art"/"as a piece of modern art"

I've already been using the one in French version.

Rand recently I’ve got athe Greek version.

I would combine this and previous sentence.

The Greek letters glowing in the dark at night are very mysterious and I love it.

RIt was only recently, that I finally got one, because the authenticofficial company in Germany had refused to accept my order then.

"authentic company" would be contrasted with "fake company", which isn't usually how I would describe it. More like "the company that makes the authentic item" and "a company that makes a fake/counterfeit item".

It was not that there were none in stock, so I was'm not sure why.

"was" is appropriate if you now know the reason.

I know that purchases overseas isare not so smoothly to be done, especially about shipping timeusually smooth, especially with how long they take to ship.

"...when it comes to how long..." or "with regards to how long..."

"shipping time" isn't necessarily wrong, but it's not usually how I'd phrase it.

UKuk before, I received it within a week.

website domain names are usually represented in lowercase, even if its a country abbreviation

However, when I ordered a Russian book at a bookstore in Japan, it took almost one month.

I am not sure why there are such differences between the casesit can be so different each time.

Grammatically correct, but a bit stilted.

Probably, there are some reasons concerning something about shipment fees.

More natural.

Its unique typography-like display with glowing letters has earned it a good reputation not only as a clock but also as a modern art.

I've already been using the one in French version.

Recently I’ve got a Greek version.

"I've got" is present tense and is synonymous with "have."

The Greek letters glowing in the dark at night are very mysterious and I love it.

"The" clarifies you're talking about the letters on the clock, rather than spooky Greek letters that appear at night and fly around your house or something.

Recently, I finally got one, because the authenticThe actual company in Germany had refused to accept my order then, but I finally got one recently.

The "because" in the original sentence suggests you got one DUE TO the German company refusing your order, rather than DESPITE them doing so. An alternate wording that I think makes the intent more clear:

> I only recently got one because the company in Germany had refused my order.

When spoken, "recently" would also be intensified a bit.

The clerk at the shop deeply apologized to me and quickly arranged to order it atfrom a Swiss shop.

IThat was last January, so i. It took so mucha long time to be delivered to me.

"so" doesn't work here because that happening in January didn't cause it to take a long time. It did, however, cause "it took a long time" to be true, so you could say something like this:

That was last January so to only receive it now (and not sooner), it must have taken a long time to get here.

I know that purchase overseas is notcannot be so smoothly to be done, especially aboutconsidering shipping time.

UK beforeWhen I ordered something from the UK, I received it within a week.

I am not sure why there are such differences between these cases.