OneStepCheckout defines section titles as locale strings like follows :

jQuery.mage.__("2")
jQuery.mage.__("1")
so you can localize the values if needed.

If on your site frontend you see 100 and 200 instead of 1 and 2 then that means your site localizes those values for you.

If you can't find a place in system where your site localises those values then you can change the 1 and 2 that OneStepCheckout sets as title numbers from view/frontend/web/js/shipping.js and replace

jQuery.mage.__("1") with jQuery.mage.__("1 ")

and 

jQuery.mage.__("2") with  jQuery.mage.__("2 ")
and regenerate static assets and clear all localisation related caches.

Note that this is a js locale cache and you might need to remove cached locale files from pub/static/*/locale_CODE/* manually as magento2 cache clearing methods do not clear those caches out of the box for you.