Multisite Installation in subdomains for different lenguages

Hello everyone;

First sorry for my english 😉

Have a question to a topic, to see if anyone can help me.

I have a website already completed under WP in Spanish

The fact is that initially only going to be in Spanish and English but now my customer told me that the website is going to be done in 6 languages

I have thought about creating a multisite installation, with Spanish as main domain, andthe other languages ​​related to other sites hosted on subdomains, , English would be
en.domain.com, French in fr.domain.com etc …

Right you see this option? Then I’ll have a problem in terms of SEO?

Thank you very much and greetings to all!

Ingennia