It's possible for anyone to 'translate' Project-GC, and correct typos such as this as they do so. So assuming you're using English (US), you could tweak the grammar on sentences such as this. I've 'translated' the whole site to English (UK), and while doing so, I re-worded some sentences (including the one you mentioned - I checked) to read more as a native English-speaker would say them.
What you need to remember is that the people who made the site are not native English speakers, so their grammar won't be exactly perfect. Having said that, it's still very good, considering that English isn't their first language :)