The version of Rampant: 3.1.1
What is your map evolution: 0.8262
Was Rampant added at the start of a game: Yes

A brief description of what you are experiencing:
My world ending enemy level is set to tier 6. However, I am getting spawns of tier 7 and 8 enemies. I am not sure if it'll go all the way to tier 10 by the time my evolution is maxed, but it looks like it.

A brief description of what you are expecting:
Tier 6 to be the cap for biter spawns.

What mods are you using?:
aai containers 0.2.10
aai signal transmission 0.4.7
alien biomes 0.6.7
flib 0.10.1
grappling gun 0.3.2
helmod 0.12.9
informatron 0.2.2
jetpack 0.3.2
rampant 3.1.1
robot attrition 0.5.12
shield projector 0.1.4
space exploration graphics 0.5.15
space exploration graphics 2 0.1.2
space exploration graphics 3 0.1.1
space exploration graphics 4 0.1.1
space exploration graphics 5 0.1.2
aai industry 0.5.17
equipment gantry 0.1.4
logistic train network 1.16.7
train log 1.1.4
ltn cleanup 1.0.17
ltn combinator modernized 1.0.10
space exploration 0.5.115
space exploration postprocess 0.5.30

Save: https://files.catbox.moe/8b9jx3.zip
Multiplayer. I am host.

This is intended I believe.

Biters ingame tier naming numbers remains the same regardless of the world ending enemy level setting. The difference lies in how strong the various tiers are. Had a look at your save and found health values from about 200-500 on t7 biters or spitters. This does not seem to be higher than it should be :)

Put differently, world ending enemy level defines the maximum strength of the biters, which is then distributed over 10 tiers.

Somewhat confusing, in my opinion, but as far as my understanding goes, this is how it works. Perhaps it is done this way in order to ensure a gradual power increase of the biters over 10 levels, rather than, in an extreme case, only having 2 levels if one sets the max to 2.

Exactly. Those 6 level tiers are distributed in 10 game map enemy tiers. And those 10 tiers are constantly progressing with evo: 30%, 40%, .. 80%, 85%, 90%, 93%. For endlevel=6 newer level are skipping some of %% milestones (e.g. 3rd level appears not at 40%, but only at 50% evo while game tier is still incremented).
Maybe it should be in FAQ.

Ah cool, thanks for the responses. Glad to see everything is working properly.