Well having sync on means the timing of the wobble should be in time with the song's tempo/bpm alright, except to get it tighter you might need to change it's speed as Fuse says.
The Maelstrom's "LFO's" are called Mod A and Mod B (modulators in that synth, but pretty much same as LFO) and the rate control is the speed alright. When sync is OFF the modulator speed goes from 0 (no change or maybe one full cycle every 4 weeks) to 127 (maybe 30 cycles a second) and the modulator cycle will start from the beginning every time a note is played.
With sync ON, the rate goes from 16/4 (meaning one cycle every 4 bars of tune) thru to 1/32 (which is 32 cycles in 1 bar of tune).
To make that more relevant, when the rate is at 4/4 you get one Mod cycle per bar, when its at 1/4 you get one mod cycle every 1/4 bar or one every beat (scuse the tech terms :/ ).
Now, if the rate is in time (also check to see if 1-shot is enabled/lit as this can mess up repeating wobbles if its on) and there's still something off, you might have to use a different Mod waveform or "curve" using the up and down arrows to the right of the waveform display (which is above the yellow 'rate' control). Best to go through a few until you find one that works right for you. The lowest (first) wave is a sine, but for timing, maybe switch it to a square wave temporarily, as the square will start its cycle right on the beat which is good to lock on to if you're trying to sort out timing. Square mod wavefrom is the 4th.
1 (lowest you can get with the down arrow): Sine, 2: Triangle, 3: Sawtooth, 4: Square.
So it could well be either the modulator rate, the modulator waveform or a combination of both that needs sorting out. If you tried all those and its still "a bit off", have a look at the sequencer part and check to make sure yer wobble notes start on the right beats/places.
Thats mah 2c.