The map I'm currently working on would probably work better if zombies spawned constantly, no pause between rounds. Only thing is, I've found no tutorials  on the matter and have no clue as to where I should be looking.

If someone could point me in the right direction I'd appreciate it, thanks

there is a value that determines the seconds between rounds and last map i remember changes on it was industrial estate and since it was 1+ year ago i forgot about it but hit up StevieWonder and see what it was exactly so you could put it to 0 seconds

in _zomiemode change:

			set_zombie_var( "zombie_between_round_time", 		10 );

			set_zombie_var( "zombie_spawn_delay", 				2.5 );

The "zombie_spawn_delay" is the delay between each seperate zombie spawn.
The "zombie_between_round_time" is the time between rounds.

Both are reduced the higher round you get, so these are the starting value's for round 1.

in _zomiemode change:

			set_zombie_var( "zombie_between_round_time", 		10 );

			set_zombie_var( "zombie_spawn_delay", 				2.5 );

The "zombie_spawn_delay" is the delay between each seperate zombie spawn.

Would deacreasing zombie_spawn_delay cause errors in-game?

Would deacreasing zombie_spawn_delay cause errors in-game?

no

Well, it's almost what I was looking for, however the only issue is that rounds only start/end when the last zombie is killed, meaning there's a period where there's just one zombie but as soon as it's dead suddenly 10+ more suddenly spawn.

Ideally round would continue to progress despite zombies still being present from the previous round, so there's a constant stream of zombies spawning. Really, a timer counting how long the game went on would be better than a round system.

I imagine it would take a lot of scripting, and while I'm willing to do that, I'm not yet able to write those scripts myself 

It's not too hard to simply keep spawning, but when you want zombies health to increase over time/increase spawn-rate/increase max zombie-count and make that related to the time-played that's going to take some more work obv.
You might want to consider a version of the UGX mod, those contain time-based gameplay if i remember correctly.

You can mess in _zombiemode with the round_spawning()and round_think() functions, wich mostly handle the spawning.

You could simply try changing this line in the round_think() function:

		level thread [[level.round_spawn_func]]();

Into:

		level [[level.round_spawn_func]]();

and then remove/comment out this line:

		round_wait(); 

Not sure how that would work if you use dog-rounds, or if it works at all  And it doesn't keep track of time-played etc..

Well your suggestion did work (dog rounds included though I intend to remove them soon  ), but I think that I'll give that UGX Mod idea a try, as a timer seems much more fitting.

Thanks though!