There are plenty of maps with hundreds of triggers and they work just fine, so if there is a limit (besides map size), you probably don't need to worry about it. iirc, wc3 runs a quick syntax check on your map when you load it in the lobby, so just make sure that it loads decently fast in that phase and you should be fine.
The only other thing I can think of is hitting the op limit.
Warcraft III has an operation limit per "thread" of execution. Usually this isn't a problem because triggers are each ran on their own "thread", and the limit is high enough that you won't hit it unless you are looping a ton. However, if you have a ton of triggers/a ton of initialization, or a ton of variables with their "size" parameter set very high, you might hit that limit. When the limit is reached, it'll just drop that thread and no further actions will be ran on that thread. It is usually easy to notice though, so apart from avoiding really high variable sizes, you shouldn't really need to do much on this part.