I have used two instances at Seattle as my proxy server (IP starts with 45), but when I access Google Scholar, they say "We're sorry...
... but your computer or network may be sending automated queries. To protect our users, we can't process your request right now."
Yet , if I use an instance at Silicon Valley as my proxy server(IP starts with 144) , there is no problem. So I think probably the problem is not caused by the proxy program, instead, caused by the network at Seattle.
I want to use an instance at Seattle because it's faster to my local network than those at other places.