I would say that you units are just all to small to be effective in 8Th
You don't wanna use 30 squigs you want at least 40.
I mean when you get to combat you want to have the full 3 ranks attack. surely squigs are going to die on the way in so take a few more to soak op the dammage and get the full strength in combat.
The same goes for goblins busses 30 is just a bit to few. you want to use these to tie things up so the need to stay steadfast for some time. Whit 30 its just to easy to lose enough to break in one or 2 rounds.
Also I dont know if your taking full command for the visual aspect of it (you know like in it looks cool) But it is really a waste of points on the goblin units.
I would still take a banner (for the blood and glory senario) But muscians and champions are point wasters. They are to slow to really benefit from fast reform and that extra str 3 attack is not going to make the unit better at holding the enemy up. I would say drop those things and use the points to make the units larger.
Apart from that I think you have a pretty nice list, personly I would add some more combat power (by for instance making you troll unit bigger)
I would not swap out the giant for a spider btw. The thing is altough a giant is realy a weak monster for it point cost it does not need general support.
A spider does its just has to low a leadership. It kinda suxs when you uge and verry costly spider runs of the board cause of a charge by some knights.
A giant does not have that problem he's ld 10 and can go on the flank all by himself and do his thing.
This holds specialy true for a goblin army wher you are already trying to cram a lot of units into you LD bubble