A client-side Minecraft 1.12.2 mod that lets you select mobs to view spawn conditions and track live, no item required.
No, this mod is client-side.
It is fine, the mod will simply not do anything server-side.
The filter box matches both localized and unlocalized mob names. This means you can type the mod name, the name in your selected language, or the default English name.
Many mobs have inherently random spawn conditions that may not be fully captured by the analysis. Increasing the spawnCheckRetries config can help, but the conditions could still be sparse. Refreshing the selection may also yield different results due to this. This is also why some mobs can be slow to analyze (taking a second).
Some mods do not provide proper localization keys for their biomes/dimensions//blocks. In this case, your modpack should provide a lang file with the appropriate keys to get proper names. Considering a raw name of <modid>:<biome_name>, the localization key format is biome.<modid>.<biome_name>.path for biomes, dimension.<modid>.<dimension_name>.path for dimensions, and tile.<modid>.<block_name>.name for blocks. I will not include other-mods-specific localization in the mod itself. Of course, if localization for these exist, it is a bug and should be reported.
Curseforge icon by Star Artsy.