I make one - russian.
File is "locale\ru\locale.cfg"
In file:
"[entity-name]
tree-01-sapling=Молодое дерево
tree-01-tiny=Маленькое дерево
tree-01-large=Большое дерево

tree-02-sapling=Молодое дерево
tree-02-tiny=Маленькое дерево
tree-02-large=Большое дерево
tree-02-red-sapling=Молодое красное дерево
tree-02-red-tiny=Маленькое красное дерево
tree-02-red-large=Большое красное дерево

tree-03-sapling=Молодое дерево
tree-03-tiny=Маленькое дерево
tree-03-large=Большоедерево

tree-04-sapling=Молодое дерево
tree-04-tiny=Маленькое дерево
tree-04-large=Большое дерево

tree-05-sapling=Молодое дерево
tree-05-tiny=Маленькое дерево
tree-05-large=Большое дерево

tree-06-sapling=Молодое дерево
tree-06-tiny=Маленькое дерево
tree-06-large=Большое дерево
tree-06-brown-sapling=Молодое коричневое дерево
tree-06-brown-tiny=Маленькое коричневое дерево
tree-06-lbrown-arge=Большое коричневое дерево

tree-07-sapling=Молодое дерево
tree-07-tiny=Маленькое дерево
tree-07-large=Большое дерево

tree-08-sapling=Молодое дерево
tree-08-tiny=Маленькое дерево
tree-08-large=Большое дерево
tree-08-red-sapling=Молодое красное дерево
tree-08-red-tiny=Маленькое красное дерево
tree-08-red-large=Большое красное дерево
tree-08-brown-sapling=Молодое коричневое дерево
tree-08-brown-tiny=Маленькое коричневое дерево
tree-08-brown-large=Большое коричневое дерево

tree-09-sapling=Молодое дерево
tree-09-tiny=Маленькое дерево
tree-09-large=Большое дерево
tree-09-red-sapling=Молодое красное дерево
tree-09-red-tiny=Маленькое красное дерево
tree-09-red-large=Большое красное дерево
tree-09-brown-sapling=Молодое коричневое дерево
tree-09-brown-tiny=Маленькое коричневое дерево
tree-09-brown-large=Большое коричневое дерево

green-coral-sapling=Молодой коралл
green-coral-tiny=Маленький коралл
green-coral-large=Большой коралл
"

It is work fine for my game.

File is "locale\en\locale.cfg"
In file:
"[entity-name]
tree-01-sapling=Sapling Tree
tree-01-tiny=Tiny Tree
tree-01-large=Large Tree

tree-02-sapling=Sapling Tree
tree-02-tiny=Tiny Tree
tree-02-large=Large Tree
tree-02-red-sapling=Sapling Red Tree
tree-02-red-tiny=Tiny Red Tree
tree-02-red-large=Large Red Tree

tree-03-sapling=Sapling Tree
tree-03-tiny=Tiny Tree
tree-03-large=Large Tree

tree-04-sapling=Sapling Tree
tree-04-tiny=Tiny Tree
tree-04-large=Large Tree

tree-05-sapling=Sapling Tree
tree-05-tiny=Tiny Tree
tree-05-large=Large Tree

tree-06-sapling=Sapling Tree
tree-06-tiny=Tiny Tree
tree-06-large=Large Tree
tree-06-brown-sapling=Sapling Brown Tree
tree-06-brown-tiny=Tiny Brown Tree
tree-06-brown-large=Large Brown Tree

tree-07-sapling=Sapling Tree
tree-07-tiny=Tiny Tree
tree-07-large=Large Tree

tree-08-sapling=Sapling Tree
tree-08-tiny=Tiny Tree
tree-08-large=Large Tree
tree-08-red-sapling=Sapling Red Tree
tree-08-red-tiny=Tiny Red Tree
tree-08-red-large=Large Red Tree
tree-08-brown-sapling=Sapling Brown Tree
tree-08-brown-tiny=Tiny Brown Tree
tree-08-brown-large=Large Brown Tree

tree-09-sapling=Sapling Tree
tree-09-tiny=Tiny Tree
tree-09-large=Large Tree
tree-09-red-sapling=Sapling Red Tree
tree-09-red-tiny=Tiny Red Tree
tree-09-red-large=Large Red Tree
tree-09-brown-sapling=Sapling Brown Tree
tree-09-brown-tiny=Tiny Brown Tree
tree-09-brown-large=Large Brown Tree

green-coral-sapling=Sapling Green Coral
green-coral-tiny=Tiny Green Coral
green-coral-large=Large Green Coral
"

Thank you, will be in 2.1.0.
Please verify that I did not break the encoding for the russian locale.

Locale looks like OK, but have error on start
tree-growth-scaled-trees": tree-growth-scaled-trees/data-updates.lua:1: tree-growth-scaled-trees/prototypes/treeEntities.lua:2: tree-growth-scaled-trees/util/tree.lua:35: 'then' expected near 'tree'

ru locale need to be saved in UTF-8 without BOM