The numbers on the wheel may already include an adjustment for the number of coins per line, and truly represent the actual number of coins awarded.
The bonus payouts in terms of total bet are not as good as they seem on the 3 reel version, where the top 1000 win is really 1000 when 3 coins are played, and the fact that there is ONLY one line available makes the overall win much better.
This version is like playing 25 spins all at once, and getting the bonus on one of them.
If you played 25 spins on the 3 reel version at 3 coins each, it will cost you 75 coins. The top win of 1000 is then a mere 13.3 x your stake.
In this game, your total stake for 25 lines at 5p each was 1.25, and you won 1000 coins (or £10). This is 8x your stake. Although worse odds than the 3 reel version, it is not THAT bad, and is probably a result of a shift of RTP from the bonus game to the base game when compared to the 3 reel version, where most decent wins come from the bonus game.
I have not played this version much, preferring the 3 reel one, but it doesn't seem to offer such big wins from the bonus game, and more seems to come from the base game.
The multi-player version might be more interesting, since you also get a share when other players hit a bonus win, so bonus payouts are more frequent, even if less.