I'm neither a full-blow writer (yet) nor professional reviewer, but as an avid reader and a lover of all good stories, I do have a couple of thoughts on this...
First off, many people do hold that, as another answer-er has already noted, certain elements of art should be reserved to their prospective fields. And to an extent, I do agree with this. C. S. Lewis of Chronicles of Narnia fame thought this way, as he explains in the preface to his work, Mere Christianity. This book first came to being as a series of radio talks he did for the BBC during the time of WWII, then eventually collected together and published as separate mini-books on the topic of Christian Apologetics. However, he later came back and re-published the whole set together as one book, making a handful of changes here and there where he thought they were needed. One of the main things he had changed was the way in which he emphasized certain words. In the first publication, he had italicized words where he had added extra emphasis in the radio talk, yet in the second publication he removed this trend. He felt that it mixed the two art forms together, and that there were move appropriate ways to achieve the same effect, yet still retain the proper identities of the individual art forms. A speaker must use volume and enunciation to put emphasis on his words, whereas a writer may play around with the construction of the sentence and surrounding words to get that result.
On the other hand, one of my favorite fantasy authors, Wayne Thomas Batson, employs a technique similar to what you are describing in several of his works. In his The Berinfell Prophecies series, whenever characters are reading from an ancient and somewhat "magical" set of histories that come alive by touching the text, the font and color of the pages changes slightly to signify it. However, it should be noted that he does not rely on this effect alone; the style and tone of the writing, as well as the style of the characters' dialog, changes slightly as well to help signify the change in narrators, as the visual effect is only in the print version of the series, and does not appear in the ebook format. Batson also employs this effect in his series, The Door Within, where the text in certain places has a colored sheen to it to match the overall color theme of that particular book. Once again, this only occurs in certain versions of the book, and is not relied on to convey much meaning or significance. Instead, it's used more as a extra special effect to make the books have that extra "cool factor", as they are mainly intended for and read by younger audiences (middle school to mid-teen ages). When I first read through this series, I thought it was amazing they had used ink like that, where if you turn it towards the light you can see the color, but if you're in a darker area it simply appears as regular, run-of-the-mill, black ink. To me, it caused the experience to be much more unique, and also meant a lot to me that someone went through the effort of adding that detail. But when I got to the third book, I ended up reading a different edition than I had the first two, and though I did miss the cool ink, the lack of it didn't harm the story or its impact on me in any way, as I soon was fully immersed in the world again and had all-but forgotten the absence of the color.
This response has gotten pretty long and rambly, but hopefully it's been helpful to someone. In the end, I would probably say that if you wanted to add an effect such as this to your story, it might add a neat twist and make book stand out a bit in readers' minds. On the other hand, make sure that if you do use it, don't rely on it too heavily, but instead compose your work first, make sure it stands solidly on its own with no extra "special effects", then add those neat touches in later as an added bonus.
