how does unleash api supported different language which library used in front-end and backend

[gsakkar]

{
"id": "06159de5-bec2-4358-8e39-18950265427a",
"name": "userWithId",
"constraints": [],
"parameters": {
"userIds": "ゆうたろう@メール.にほん"
}
}

[ivarconr]

I am not sure if I fully understand your question. If it is whether Unleash will support different "characters" you should be safe as long as you you stick to utf-8.