Maybe you should put some screen shots on REDCORE-185 task so we can all have better picture what is happening. Tbh, I wasn't having any problems so far with redCORE and bootstrap on backend, but in most cases I used Joomla 3.*. However, while I was working on redSHOP2 I was testing it on j2.5 and haven't had any problems, but that component is loading it's own admin views. :)