@ Peridotgreen,
How right you are. Years ago I noticed that some Bibles translate Isiah 65:11 (the ' god of good luck' scripture) as 'setting the table for the god of good fortune,' or simply 'for Fortune.' Examples here.
So it's the same thing. Witnesses were fooling themselves by saying 'fortunate' rather than 'lucky.'
And the Watchtower magazine, 9-1-80 issue, p30 suggests that using the word luck to simply mean "good results" is perfectly ok anyway.
It's one of those famous Watchtower myths that catches hold and goes on for decades.