Hi all! I'm about to join a lvl 20 campaign, and I'm gonna play a wizard. Lots of paperwork, gamebreaking stuff, that's sort of what we're going for.

My question is about the Wish spell. Wish is known for its dangerous consequences if used unwisely. However, reading it, it seems like the consequences only have to do with effects other than duplicating a spell or the items on the wish list.

The basic use of this spell is to duplicate any other spell of 8th level or lower. You don’t need to meet any requirements in that spell, including costly Components. The spell simply takes Effect.

Alternatively, you can create one of the following Effects of your choice: 

[That list]

You might be able to achieve something beyond the scope of the above examples. State your wish to the DM as precisely as possible. The DM has great latitude in ruling what occurs in such an instance [meaning not using a 8th-level or lower spell; or using the examples]; the greater the wish, the greater the likelihood that something goes wrong. 

Emphasis and brackets mine.

If I'm reading this correctly, the risk of "something going wrong" is avoided by using an 8th-level or lower spell (such as simulacrum or planar binding--even if they are upcast to 8th-level per Jeremy Crawford), or by using an example from the list. (Plus, the risk of losing the ability to cast Wish is avoided by duplicating a spell.) 

Is my reading correct? Or, would something "go wrong" even if I duplicated a spell of 8th-level or lower?

Perfectly safe in 100% of instances. From Wish:

The stress of casting this spell to produce any effect other than duplicating another spell weakens you. After enduring that stress, each time you cast a spell until you finish a long rest, you take 1d10 necrotic damage per level of that spell. This damage can't be reduced or prevented in any way. In addition, your Strength drops to 3, if it isn't 3 or lower already, for 2d4 days. For each of those days that you spend resting and doing nothing more than light activity, your remaining recovery time decreases by 2 days. Finally, there is a 33 percent chance that you are unable to cast wish ever again if you suffer this stress.

Ill effects only have a chance of occurring when you use Wish for anything other than duplicating a spell of 8th level or lower.

To be clear, I'm talking about unforseen consequences ("something goes wrong"), not damage/stress. :)

Interesting that the text of the spell uses GM rather than DM. Anyway, there is no risk if you use it to replicate a spell of 8th level or lower. Obviously a GM can do whatever they want at all times, but assuming they’re not overriding what’s written in the text, there would be no unforeseen consequences.

Wish can be used in 3 ways:

1. Basic Use - replicating a spell of 8th level or lower.

2. Non-Basic (Defined) - using wish from the defined list of effects. These happen as described, with no backfiring.

3. Non-Basic (Undefined) - using wish for something not in the list. This is entirely up to DM to adjudicate and some Wishes might backfire on you.

Of these, #2 and #3 incur the 'stresses' detailed in the spell which include the 1/3 chance to never be able to cast Wish again. #1 does not suffer these stresses so it is a perfectly safe use of wish.

There is a way around the stresses, by having Wish prepped/available and casting Simulacrum the normal way. The simulacrum follows your orders and has your slots and spells. You can order the simulacrum to cast Wish for you and it, rather than you, will suffer the stresses of the spell.

Quote from Xethreau >>

To be clear, I'm talking about unforseen consequences ("something goes wrong"), not damage/stress. :)

 You're still 100% good to go. There are absolutely no negative/unforeseen consequences when using Wish to duplicate a spell of 8th level or lower.