the first problem that jumps off the page at me is that it will be difficult to keep your wraithlords from testing for wraithsight, the jetbike warlock is probably your only way of doing this (i assume your farseer is riding with the banshees and anyway i don't know if you can measure to a skimmers hull in respect to this) and in doing so you are probably restricting the jetbikes because their maximum range is only 24 and they need to be within 12 to do their horde killing thing
the jetbike squad itself is not bad, but personally i would take embolden over destructor on the warlock as two casualties can make them fall back extremely quickly and you need them as they are one of your two scoring units for objective missions
if i was to rearrange your list, using only the models you have i would probably build something like this;
Farseer, Runes of Warding, Doom /// 95
10 Howling Banshees, Exarch, Executioner, Acrobatic /// 187
~ Wave Serpent, Spirit Stones, TL Shuriken Cannons /// 110
8 Fire Dragons, Exarch, Dragons Breath Flamer, Crackshot /// 145
~ Wave Serpent, Spirit Stones, TL Shuriken Cannons /// 110
6 Striking Scorpions, Exarch, Scorpions Claw /// 113
10 Dire Avengers, Exarch, Shimmershield and Power Weapon, Defend, Bladestorm /// 177
~ Wave Serpent, Spirit Stones, TL Shuriken Cannons /// 110
10 Guardian Defenders, Scatterlaser, Warlock, Embolden, Spiritseer /// 137
Wraithlord, 2 Flamers BrightLance, Eldar Missile Launcher /// 155
Wraithlord, 2 Flamers BrightLance, Eldar Missile Launcher /// 155
2 Warwalkers, 4 ScatterLasers /// 120
/// 1496
it takes the core of your list (3 serpents, 2 Wraithlords) and turns it into more of a hammer and anvil army (hammer and anvil basically means that you split your force in two, one to hold position and resist attacks and the other a rapid moving strikeforce that can strategically attack where they will be most effective)
your hammer takes the form of the three waveserpent mounted units, and your anvil is the wraithlords, guardians, warwalkers and the scorpions, i don't really like scorpions in a squad less than 8 strong but you said that you are unable to proxy anything and don't have sufficent models, maybe you could try getting away with proxying your autarch and yriel as 2 extra scorps, you'd need to exchange or downgrade the warwalkers for something else to get the points though.
lastly, your english is very good, i had no trouble understanding you at all, i know people with english as a first language that can't write a coherent post!
hope some of that helps a little bit