"There are forty-seven spiders there already."
Translation:Pavouků tam už je čtyřicet sedm.
The first one is possible, but stressing a different thing. In the official answer we know we are talking about spiders there and the new info is their number. In your sentence even the fact there are any spiders there is probably new.
The other one is not Czech, we do not put the adverb of location at the end as English does.
This is an unusual combination. The Czech national corpus has only 8 sentence starting "Je už tam..." and 180 for "Je tam už..." (now corrected). And some of those 8 come from interviews and the sentences may be unprepared or otherwise affected by the immediate situation. Feel free to report it using the report button and it may be added as a not-very-common form in the future. But it sounds weird to me.
We can start with almost anything:
- Je tam už 40 pavouků. - default, neutral word order
- Už je tam 40 pavouků. - pretty neutral, "už" can easily start the sentence
- Už tam je 40 pavouků. - same as above
- Tam už je 40 pavouků. - As for that place, there are 40 spiders there.
- Tam je už 40 pavouků. - same as above, just coupling už + numeral to slightly emphasize that it's already 40
- Pavouků tam už je 40. - As for spiders, there's already 40 of them there.
- Pavouků už je tam 40.
- Pavouků už tam je 40.
- Pavouků je tam už 40.
- Pavouků tam je už 40.
So... when we begin with the spiders, which makes them the topic (Speaking of spiders... As far as spiders are concerned...), we can place the three little words almost in any order. An unnatural order would be "Pavouků je už tam 40", all the other ones I mentioned can be justified.
Tip: If you don't want to worry too much about "už" (because its position is quite flexible), best place it either first - "Už..." - with the other little words following it, or place it right before the number/amount - "už 40 pavouků", "už 20 let", "už 2 dny", that way you don't have to figure out where exactly in the second position it should be among the other little words. ;)
No, it looks like VladaFu accidentally switched it up - that's what svrsheque is referring to, I believe - that's what's led to your confusion.
"Je tam už..." is the natural word order. "Je už tam..." sounds like a complete sentence, most likely a question, where "tam" is emphasized, it would be weird to add anything after "Je už tam?".