No, once your challenge has started, it is not possible to switch from MetaTrader 4 (MT4) to MetaTrader 5 (MT5) or vice versa.
Why Can't It Be Changed?
Each challenge account is linked to a specific platform from the beginning.
The system does not allow transferring trade history from one platform to another.
Recommendation:
Before starting your challenge, make sure to correctly select MT4 or MT5 based on your preference and convenience. If you're unsure, check the platform’s compatibility with your trading strategy before completing your purchase.