Had Aisha reached puberty at age 9 when Muhammad, in his fifties, consummated the marriage with her? No...

In another post, we cited some of the canonical hadiths in which it is stated that Muhammad consummated his marriage with Aisha when she was nine (lunar) years old. Had Aisha reached puberty by then?

Consider Sahih Muslim, a canonical hadith collection:

Book 008, Number 3311:
'A'isha (Allah be pleased with her) reported that Allah's Apostle (may peace be upon him) married her when she was seven years old, and she was taken to his house as a bride when she was nine, and her dolls were with her; and when he (the Holy Prophet) died she was eighteen years old.
In the next hadith, we learn that playing with dolls is only permitted for prepubescent children:

From Sahih al-Bukhari, a canonical hadith collection:

Volume 8, Book 73, Number 151:
Narrated 'Aisha:
I used to play with the dolls in the presence of the Prophet, and my girlfriends also used to play with me. When Allah's Apostle used to enter (my dwelling place) they used to hide themselves, but the Prophet would call them to join and play with me. (The playing with the dolls and similar images is forbidden, but it was allowed for 'Aisha at that time, as she was a little girl, not yet reached the age of puberty.) (Fateh-al-Bari page 143, Vol.13)
The parenthetical statement is not mine -- it's in the University of Southern California's Sahih al-Bukhari online, as you can see by clicking on the link above.  So, from the two canonical hadiths just cited, we find that 1) when Aisha, at the age of nine lunar years, entered Muhammad's house as a bride, her dolls were still with her, and 2) playing with dolls is permitted only to prepubescent children.

And then of course there is the increasingly infamous Qur'an verse 65:4, which specifies a waiting period for prepubescent females to remarry after being divorced. A waiting period before remarriage is required only if the dissolved marriage was consummated. (See Quran 33:49.) Thus Qur'an 65:4 assumes consummation with prepubescent girls.
Qur'an Chapter 65, Verse 4:

And (as for) those of your women who have despaired of menstruation [because post-menopausal], if you have a doubt, their prescribed [waiting] time shall be three months, and of those too who have not had their courses [because prepubescent]; and (as for) the pregnant women, their prescribed time is that they lay down their burden; and whoever is careful of (his duty to) Allah He will make easy for him his affair.
In yet another post on this question, I'll quote a number of authoritative, mainstream Muslim scholars who agree that 65:4 refers to the waiting period before remarriage of divorced, prepubescent girls.