This is the sort of sentence (desire, wish, etc.) where French would use the subjunctive, and Esperanto tends to use the imperative.
also, "..., ke li ricevi donacon" would not work grammatically at all. (Mom wants that he to receive a gift?) Nor would "Panjo deziras lin ricevi donacon" - this raising that English does ("I want that he does ...") becoming "I want him to do...") doesn't work in many other languages.
korekta is arguably wrong :)
korekti means "to correct (something)" and so korekta means "correcting; related to corrections", e.g. korekta likvaĵo "correcting fluid", fluid which is related to correcting.
Though it's often used in the sense of "correct, without error" (= senerarar, ĝusta). The PIV dictionary calls that use evitenda "to be avoided".
Mi volas fari tion is correct; Mi volas faru tion is not. There's no separate clause here and the grammar is different from a sentence such as Mi volas ke vi faru tion.
If you read the PIV definitions, you will see that voli is (or was) primarily about volition: i.e. will/intention. Deziri is about desire, wishes. I think, frankly, that many of the sentences here at duolingo (though not necessarily this one) are currently much over-using voli for both cases. This probably reflects common usage, but I personally think it is a little sloppy and I am submitting alternative answers for all these cases.
The Plena Ilustrita Vortaro, a big monolingual Esperanto dictionary.
The 2005 version was digitised and is available online.
There is no one standard Esperanto dictionary but PIV is, it seems to me, widely used, perhaps because of its size. So it's not officially normative but I think it's well respected in general.
Found this. Might be useful for anyone else who was confused by this sentence: https://adventuresinesperanto.wordpress.com/tag/subjunctive/
Sort of -- it's a diminutive or "pet name" for patrino.
Esperanto uses -nj- for females and -ĉj- for males to make diminutives -- usually replacing some of the letters rather than adding on to the end like other suffixes.
So you have panjo, paĉjo for "mum, dad" from patro, patrino; Vilĉjo for "Bill" from Vilhelmo (William); Joĉjo for "Jack" from Johano (John); Manjo for "Molly" from Mario, Maria, Mariino "Mary"; onjo "auntie" from onklino (aunt); and so on.
I sometimes wonder that, too.
As a contributor, though, I can tell you that that box was a mixed blessing.
Some users explained why they a particular sentence should be accepted and quoted the text -- that was helpful.
Some users said "my sentence should be accepted" -- that was less helpful.
And too many users said things like "ablbalblabslkjajbskdkjb" or "f you duolingo".