Graphs will render over the boundaries of the graph view when reaching level 4 or above.
While writing the mod, I was able to find capacitors that had modifiers that went as high as level 10.

We need to find a better way to render these.

• dynamic scaling: all graphs get scaled down equal to the maximum modifier level on a given capacitor.
• Rework graphs to render on the full width of the gui and expect capacitors up to a certain level (level 6?) and limit graphs to not render bigger than that. Modifiers that have an effective level of 6+ would then get a different color or some form of identifier (icon, actual number, etc)

It looks like reddit found a way to create capacitors that will break any gui (increasing the amount of RF/t generated from a single piece of coal to 500 million per tick) This cant be displayed with a gui, but since this can be considered a bug, I will wait for the developers to respond to this bug.
The GUI update will not happen before EnderIO released a stable version for 1.11.2 (or higher) since I do not intend on doing much more work on any MC 1.10.2 versions other than bug fixes.

BTW, max valid level is 4.75 for loot caps.

Most scalers are limited to 5, a few technically unlimited (e.g. area). So third-party caps could have higher values---but you're only allowing Ender IO caps into your machine anyway, I've seen.

Do you know of any mods that add custom capacitors? I was not aware there were any.

No, I have not yet seen some. Which is a shame, I added the nbt-based system because it was requested so often... (The loot caps were only intended as an example of how to use it.)