OK...more interesting news.
On MY machine (and, I guess because we all have different spec machines), which is a Late 2013 21" iMac with Intel Iris Pro Graphics, Core i5 Processor (2.7) this strange graphic/object glitch is somehow related to .... AUDIO.
You can see in this screenshot that the graphics are "missing" before you even get into the book cave! This is with the audio ENabled.
If I crank up ALL the graphic settings to Max but DISable Audio in the Audio Tab (not just the Voice Settings, the actual "Enable Audio" tick box), then the glitch disappears and I can see all the correct textures and click on (and obtain) the Relto book.
For me it make NO difference what Graphic settings I have in the Graphic Tab, the ONLY way to correct this glitch is to DISable the Audio completely ...
Once you have your Relto book, you can close the game, restart the game and Enable the audio.
I hope this helps anyone with a similar machine who want to get started (or create a new Avvie) in Deep Island using a Wineskin wrapper 2.6.2 and engine 1.5.0.
when it comes to Age creation ... "DOH" seems to be my middle name...