It will show when it left China, and the destination generally, at least for everything I've purchased from FT, or FC. More than the USPS provides, which shows "origin post is preparing shipment" for weeks until it hits stateside, It may be different for the EU postage sites, I don't know.
In my case, using ePacket, 17 Track showed when it left China, then Royal Mail (our equivalent of USPS) showed that it had cleared customs four days after that; two further days later - a day after delivery - 17 Track then also showed that information.
So 17 Track did show UK information, but at least in my case it had no point as it was after delivery. But I suppose if local delivery had been more protracted, it might have caught up. But I don't see any sign that it would or could show more information than the local tracking site did.
I suppose there could be a situation where the local country doesn't provide proper tracking, but 17 Track is able to show something. But at least in the UK, 17 Track is basically just contacting the local courier to ask for the information the same as the end user is able to do, so it's only useful for the China side.
Interestingly, Royal Mail still shows mine as only having cleared customs - no further tracking and no confirmation it was delivered nearly a week ago! Maybe if I hadn't already contacted 3F, I could wait two months and then claim it never arrived

Probably it will update eventually, and/or they've at least communicate delivery back to the China side even if it's not showing on their tracking site. (Don't worry I wouldn't do that anyway

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