No you should check first how many you gonna get before change them.
When you purchase enjbnt, you created an opportunity for someone to convert tokens using the relay.
When you tried to sell your tokens into either one , the current rate has changed leading you to sell at a lower rate.
(This means that you could have sold to opposite token at a higher rate)
And use the getSaleReturn function to know how many you will get before chnge it.