> Is it possible to modify comments without the use of an EA
Once an order has been placed, I don't believe there is a way to do that, even with an EA
We end-users cannot do it via the client platform, but the broker's can, and do, change them as they see fit.
Oanda for example completely overwrites the user's stated comment for the trade. Many other brokers will append a notation to the end of the order comment (overwriting pre-existing characters in the ordercomment if the space is needed) to indicate if the order was closed by virtue of triggering the defined stoploss or takeprofit values.
So we know for sure the ordercomment can be changed, we just are not granted the privilege to do so from our end of the equation.