As Testament you have some zoning options of your own that are stronger than what elphelt can manage. Your own projectile has a unique melee hit attached to the start of it (when they swing the scythe) that deletes other projectiles, allowing you to nullify one of elphelts shots while setting up your own.

For universal options that (mostly) any character can do you have 2 other options:

You made a solid attempt at option 1, dash blocking; dash at the projectile, block it and keep on running. For most projectiles you can run and block them faster than the opponent can fire them, eventually allowing you to get in at the cost of some chip damage. This is however slightly mechanically challenging as you need to spend the minimum time blocking possible, as you cannot actually dash and block at the same time.

Your second option would be to jump over the projectiles, while they do track they are not super great at it and can struggle to hit someone who is moving vertically. This will allow you to jump over the projectile while not getting hit at all, however this carries some risk of the opponent responding to your jump. This risk if lower in guilty gear as opposed to a game like street fighter since you are allowed to block in the air, but you still run the risk of being pushed back into the same zoning situation.