You may find this .lang file approach to translations easier for your mod.
.lang files contain translations for the language specified in the filename.
The possible languages are: English ("en-US"), German ("de-DE"), Italian ("it-IT"), French ("fr-FR"), Spanish ("es-ES"), Russian ("ru-RU"), Chinese ("zh-Hans"), Portuguese ("pt-BR"), and Polish ("pl-PL")
Here in ExampleMod we have organized these files in a folder called Localization. A single file per language makes it extremely easy to to integrate and maintain translations.
Each translation entry in .lang files contains a key, an equals sign, followed by the translation immediately after. One translation per line.
The Key automatically inherits "Mods.ModNameHere.", which is useful to know if you want to use substitutions (as seen in the Paper Airplane example) or use Language.GetTextValue or Network text.
The following are the currently autogenerated keys: ItemName, ItemTooltip, BuffName, BuffDescription, ProjectileName, NPCName, MapObject, and Prefix

The following 2 examples are simple.

NPCName.FlutterSlime=Flutter Slime
MapObject.ExampleClock=Example Clock

These 2 examples show using substitutions. Here we use a vanilla Key and a key from this Mod to generate the text: "Nearby players get a bonus against: Octopus". 
Note that the translation files for other languages don't need to define ItemTooltip.OctopusBanner, they would only need to define NPCName.Octopus, as seen in zh-Hans.lang file. 

ItemTooltip.OctopusBanner={$CommonItemTooltip.BannerBonus}{$Mods.ExampleMod.NPCName.Octopus}
ItemTooltip.SarcophagusBanner={$CommonItemTooltip.BannerBonus}{$Mods.ExampleMod.NPCName.Sarcophagus}

Here we see that spaces in translation keys are not allowed. Any space will be replaced with an underscore.

NPCName.Example_Person=Example Person

Since the item, buff, and projectile all share the word "Paper Airplane", here is a custom translation key that we define. 
By sharing a common tooltip, we can simplify other language files since English is the fallback language.
Other languages would only need to provide a translation for Common.PaperAirplane, BuffDescription, and ItemTooltip. They can skip ProjectileName, ItemName, and BuffName.
Also note that \n makes a newline character, useful for multiline tooltips.

Common.PaperAirplane=Paper Airplane

ItemName.ExamplePet={$Mods.ExampleMod.Common.PaperAirplane}
ItemTooltip.ExamplePet=Summons a {$Mods.ExampleMod.Common.PaperAirplane} to follow aimlessly behind you\nSecond Line!
ProjectileName.ExamplePet={$Mods.ExampleMod.Common.PaperAirplane}
BuffName.ExamplePet={$Mods.ExampleMod.Common.PaperAirplane}
BuffDescription.ExamplePet="Let this pet be an example to you!"