How to colorize an translucent picture in Photoshop?

I’ve got a scanned picture of a sticker album which contains an translucent room where the sticker should be sticked. I’ve tried (using the Equalize, Curves, Levels, Vibrance and Contrast Tools from Photoshop) to get the translucent room as close as possible to the real sticker, but I feel that I still can do something to improve it. Could someone give me, kindly, some hint about this situation?

Why should I calibrate my screen?

As both a web and print designer, I have never seen the need to calibrate my displays. Especially for web design, I wonder why I should spend several hundred euros to calibrate when I can instead test my colour choices on multiple uncalibrated displays in different lighting conditions. Only a handful of users are going to look at my colour choices on an accurately calibrated screen while under the same lighting as I had when I stuck my ColorMunki to my screen.

How configure color in InDesign for a specific printer?

In my work recently was bought a Brother MFC-L8850CDW printer, CMYK tonels. But no matter what we do, when a document or a PDF made in InDesign is printed, the output colors on paper have a huge difference between what we see in the screen. For example, the cyan or sky-blue are printed like dark-blue, or the magenta that is printed almost like red.