Rewrites are not working as index.html ends up being served from static

[BeOleg]

This helper helps us run more than one react project in different directories under the same domain.

we need the following rewrites:

Original URL	Rewritten URL
https://n.exchange/?lang=RU	https://n.exchange/?lang=ru
https://n.exchange/?lang=RU&cur_from=CARDUSD&cur_to=BTC	https://n.exchange/?lang=ru&pair=BTCUSD
https://n.exchange/?lang=RU&cur_from=CARDUSD&cur_to=BTC&ref=MyAwesomeRef	https://n.exchange/?lang=ru&pair=BTCUSD&ref=MyAwesomeRef
Any combination of the above

Problem: index.html gets served via the express static server and this logic never happens.