"The doctor is walking now."
Translation:Az orvos sétál most.
"Az orvos sétál most." is also correct, as it emphasises. to the doctor walking now and not doing some other thing.
You're right but the English sentence is more the one LOLSmiley0 suggested.
"sétál" is proper for the meaning of walking. "megy" is more general in the meaning of "to go".
It's good, if rejected you may want to report it. There is a slight difference in emphasis, but for the English it is less significant than in Hungarian. In the Hungarian sentence above it is very specific that in this moment it is the doctor who is walking and not any other person while neither of the English translations give the equivalent weight of the statement. (Nevertheless this sentence gives me a fictional scene of a maffia film where the bad guys watch the yard of the prison and check when the boss will let out for a walk alone—the usual routine is strict, first is the serial killer, then a bank robber, then the doctor who sold the organs of his patients and... and... and... here comes our Padrone, now we can attack to escape him!)