You're mainly right, but...
To make an EMA 200, you first have to collect 200 averages (1 price, then average of 2, then average of 3... up to average of 200).
Only then, you can start the EMA, which is a formula of the current price and its weight applied to the previous result (the 200 averages).
The next EMA is the same on the previous EMA, etc.
That means 2 things:
* before the first 200 averages are done, the EMA is NOT an EMA - the bot decision could be weaker (or better) one, but is a different one.
* there is NO WAY to save (on file) this, especially while you can change the EMA 200 to EMA 500 or 42 between 2 runs of the bot.
But, if Gunbot is smart, it can keep in memory the past prices, and when it's reconfigured it can recalculate the whole EMA "chain".
If it works like this, yes, EMA can be brought back immediately (recalculated) after the reconfig.
But no, it can't be saved, so at a fresh start it has to wait for the 200 prices.
Which can take time - you say trades, I would have said price ticks (25s each), but yes you're probably right, it may get the trades of the current price tick duration...
It still can take some time for pairs with low volume of transaction...