Keras offers a user-friendly interface for creating and refining CNNs and other deep learning models. In order to speed up training, you should additionally be familiar with deep learning frameworks like Keras or TensorFlow, have access to image data, and use GPU hardware.
Python GUIs can be easy to develop and use with a native Windows development tool like Delphi or C++Builder. The Python4Delphi library enables easy interfacing between Python and the rich native VCL framework available in Delphi and C++Builder. Delphi and C++ are powerful programming languages that mesh well with Python.