This is just a bit of random feedback. I realize the images for SM were chosen as the beginning sounds are similar to the solfege names. For some of the words, they are similar but still slightly off. So, should you ever decide to update the software, perhaps you may consider updating a few of the images as well with words that better imitate the solfege names.
Do- The sound of the word door is an "or" sound, as in "either/or" or "this gift is FOR you." If you are looking for a doh/doe sound, the word Donut would work better with a cute, simply drawn donut.
encrypted-tbn3.gstatic.com/images?q=tbn:...nbhr8-qbQ0oah0CkLjBX
Re-Rain already works beautifully.
Mi- Mirror is another one that is slightly off. It's hard to write it out, but the pronunciation is more like "M-ear-ror" or "M-ihr-ror, not "Mee-ror" like the solfege name Mi. If you want the Mi sound, it would need to be a word that begins in Mea, like Meat...a simply drawn ribeye steak perhaps? Vegetarians may find that off putting, I suppose, but it would achieve the sound goal. One could argue it may be confused for "steak" initially.
encrypted-tbn1.gstatic.com/images?q=tbn:...zODKledsjN-YupIIqzJw
A falling meteor would work as well but I think it might be difficult to represent graphically in a simple way without it being confused for a comet
www.graphicsfactory.com/Clip_Art/Nature/meteor800_150899.html
Fa- Farm is an R-controlled word with a "bossy R sound," so rather than an -ah sound, you have -arrrr, like arm or "Arrrrgh, Matey, I'm a pirate!" I previously thought of something to replace this but cannot remember at the moment.
So- For So, the word salt is not ideally representative of that sound. A bar of soap might be a better fit to really get that "oh" sound of So/Sol. It may be a pronunciation difference, but here we do not say "S-oh-lt" but rather, "S-ah-lt." So the beginning sound is not So, but Sah. Or even the word "Soldier" (with a toy soldier) might work if you are are the Sol sound in full, but that image may be slightly more ambiguous.
www.google.com/imgres?imgurl=http://www....=0CDsQ9QEwAw&dur=121
La- The word Lock gives you the La sound (with a picture of a padlock), rather than Ladder, which has an a short a sound as in apple or lad.
encrypted-tbn0.gstatic.com/images?q=tbn:...197-nfH011zQHE875Ylw
Ti- A teacup works well for this.
Additionally, you could add some display options in addition to the solfege pictures and alphabet labels on the notes. It would be nice to have the option to read solfege names directly on the notes and after a student has mastered reading the notes, there might be an option to include numbers on the notes. Not entirely sure on these, just an idea that came to mind. I get confused sometimes on which fingers to use. Although I realize there is a video library it would be nice if it was self contained in the program.
I'm sure there are other options, but these came to mind offhand. Do with the suggestion what you will, take it or leave it (some or all), but I wanted to put it out there.