Unless another answer comes by, I'll write this for now.
I just wrote into my app itself Readline access with a gem :
gem 'rb-readline', '~> 0.4.2'
The reason I specifically chose 0.4.2 is because there is an existing bug with later versions as of August 14th 2013.
Somehow when I upgraded OS, the call to my Brew install of Readline was no longer relevant. Not sure why. I imagine there's a way to align the paths again so that it could potentially work globally throughout all my apps, but I only have one internationally sensitive one for now.