The extension to CBE was not due to PF constraints. It was because of several other factors.
Before the opening of the Konkan railway, all the trains from Kerala to Bombay passed through CBE/KPD. Trains like Netravati, and all the weeklies from Gujarat/Rajasthan to Kerala used to pass through the GTL-RU-KPD-CBE-SRR or the GTL-KJM-JTJ(bypass)-CBE-SRR routes. So, there were many trains to Bombay from this portion.
Once KR was opened, except the Jayanti Janata, all other trains were diverted via KR, depriving this section of trains to Bombay. With most of the SBC-GTL-Bombay route...
more... being on single line, the line capacity was very less. So, to serve as many places as possible with a single train, the Bangalore-Kurla train was extended to CBE, instead of introducing a separate train. Similarly, due to less line capacity on the YPR-UBL-Miraj route, the Chalukya express was extended to PDY/TEN instead of introducing a separate train.
These problems will persist until both routes are doubled.