There are so many railways in Tokyo so it's difficult for foreigners to understand
Tokyo has so many railways so it's difficult for foreigners to understand
書いて頂いた、「東京の電車は路線がたくさんあって外国人にはわかりずらい」という文章を英語にすれば、”There are so many railways in Tokyo so it's difficult for foreigners to understand” や、”Tokyo has so many railways so it's difficult for foreigners to understand” などの形になります。
「○○にわかりずらい」とは、”It's difficult for... to understand"という意味です。
ご参考になれば幸いです。