.... Yes, it may not be accurate, in some cases the wrong address may be returned/checked, but I don't know of better tools.
Sorry I didn't put it clearly, it's not that there are no better tools, it's the fact that there are no tools or even a way to be sure.
If you can't see the full address and the private key so you can verify that the private key is actually, for that address, while making sure nobody else has seen / still has the private key then you no longer have
BTC.
You have a lottery ticket that may or may not have
BTC in it when you finally scratch it off.
Look a handy thread that not enough people read:
https://bitcointalk.org/index.php?topic=3315347.0-Dave
Well this thread is more about classic scams you can get with many other goods you can purchase online unfortunately. But what you said above is interesting, for you the acceptable limit of a shortened address should be 10 characters at least. Address strings shorter than that are such risky? I mean 7+ characters is not enough according to you? Are there some figure (stastistics) about that somewhere?