a suggestion - I ran into similar "adventures" when I installed Platinum, crashes were frequent, and the audio engine refused to start in WDM or WASAPI modes.
I found two problems:
1) ASIO worked, but WDM and WASAPI were setting latency to the absolute minimum in audio settings. My machine is relatively new, but it ain't that fast. This seems to be default behavior in Platinum, I have verified that it does not happen in X3. Once I had this resolved I did go back to ASIO because it was still crashing too regularly.
2) Kontakt was out of date - I tend to avoid Kontakt updates since too many times they have caused problems, but this time it solved the problem. No more crashes.
I am comfortably running six instances of Kontakt with 14 to 16 instruments in each, and one stereo output for each in most cases (I do stack articulations where I can.) Projects can have upwards of 80 tracks without a hiccup.
The other thing I notice is that you are mixing 32 bit and 64 bit plugins. This has been a problem for me since X1, sometimes it works, sometimes it makes me crazy. For now my solution is to avoid 32 bit plug-ins like the plague. Which is unfortunate, since I still have a few I really like! I tried the demo for J-Bridge and it appears that some plug-ins, especially Virtual Instruments, seem to work better with one bridge and some work better with the other. When I have the time I will probably sort it out. Of course when I have the time they'll probably all be updated (that would be nice!)
Anyway, without knowing your specific configuration all I can do is tell you that I am runnign a pretty heavy template (for me) and it works well in Platinum.
My system was assembled last fall, and includes:
Intel i7-4790 (stock speed) on ASRock Z97 Extreme4 with 32GB of DDR3-1600 CL9 RAM, and NO VIDEO CARD! I splurged on a couple SSDs, and that has made a HUGE difference. And I am running Windows 8.1 Home Premium, I had hoped to use Win7, but 8 was significantly cheaper.
One other thought - I am evaluating Vienna Ensemble Pro as a host for Kontakt and other virtual instruments that I do not wish to have to load every time. It works well, even on a single machine. Three instances of Kontakt might not be enough to justify the purchase, but as you add more instruments you might want to take a look.
Good luck!