Working on the icons bug for 3.8.6 today.
Not sure what you mean by the themes not working. Many of the themes have been designed to work with a specific WordPress theme. Since I took over the plugin from Cyber Sprocket I've been trying to keep notes on what WordPress themes the CSL themes are designed for, but so far only for those I have created for customers. The prior ones I'm not even sure what they were designed for.
In SLP 3.7.X I decided constant SLP theme additions on an "as requested" basis was not going to work as a solo dev, so I introduced the "customize your CSS" option and later added a "customize the results output" option to put more control over the UI in your hands. You'll need to know basic CSS and HTML but it is better than hacking code. Those options require premium add-ons BTW, Pro Pack and Enhanced Results.