Quote for a discussion with Smiles on indirect combat spells: Taken from SR5 p.283 COMBAT SPELLS --->Indirect
"...The spell then is launched with an Opposed Test that pits the magicianís Spellcasting + Magic [Force] versus the targetís Reaction + Intuition, kind of like shooting a gun (in this case with bullets made of acid, or fire, or something equally unpleasant to be hit by). So you donít really need to be able to see the targetóyou can cast these spells blindfolded or with artificial image enhancementó as long as youíve got a clear line of fire. "
The section doesn't address any modifiers to the attack roll, such as range, obscurement, cover etc. Just wanting to make sure we are all on the same page. For the record Smiles, I'm presenting this as how I understand. This is your game, and a simple "I don't think it should be that way" is sufficient.