I was looking at ways to get a group of people with different languages to communicate with each other.
Thoughts within babble" gives understanding, but not the ability to speak the other language.
I've thought about options.
One option is a group version of "Thoughts within babble". That way everyone can speak in their own language, and the spell translates for everyone. I'm thinking a level 45 Muto Mentem with Intelligo requisite is pretty tough to cast though, not to mention the warping. (My thinking, +2 for change from personal to voice, and +2 for change from individual to group/room).
A voice range thoughts within babble would be level 35 (+2 from person to voice) and not needing the Muto skill. While touch would be level 30, that does require a magi to touch a target who doesn't know why the magi is doing so. A tad risky. Problem with this is thoughts within babble is concentration duration. Maintaining a spell for every target won't be easy.
Any thoughts I had about giving the ability to speak a language hits problems. If you can give the knowledge of language, how good is it? level 5? If a Magi can give skill in language, why not any other skill? That seems to cause huge game balance issues.
Is there a good magical way to make communication easy, or is the only good way to communicate across languages is to have a bunch of multilingual experts in the covenant?
If you touch an individual in a group, or are part of one, the group does not all need to be touching you only need to touch or be one of the group targets.
In light of the recent discussion regarding granting magical senses to groups it would be +1 for using MuMe to grant senses, +2 for Group. +2 Voice is not necessary, you can use +1 Touch. So indeed, lvl 45. You might be better off with multicasting.
Hermetic magic can't grant any ability at all, so I think Thoughts Within Babble is indeed your best option.
If is is a quiet discussion within a room and people are willing to stay sitting at a table, a Ring variant could work:
Mu(In)Me The Sages' Council
Base 15 (Base 5, Per. Hearing), +1 magnitude (granting magical sense), T: Circle (+0), R: Touch (+1), D: Ring (+2), for a final level of 35.
As Rafael said, hermetic magic does not "teach" abilities.
Instead of reading minds to understand languages, a similar purpose might be served by base level 3 to 4 CrMe Mental Communication like in ArM5 p.105, and described more precisely in A&A p.32 box Creo Mentem Guidelines.
Especially creating imagination (base level 4) circumvents language barriers and is very useful for communication.
As example devices for CrMe communication, here are the globus parvus imaginationis and the globus magnus imaginationis.
The globus parvus imaginationis is a hollow metal ball the size of a large marble. It is enchanted with unlimited uses of the effect: Share Imagination (CrMe base 4, R: Touch, D: Moment, T: Individual), which allows to transfer an imagination of the ball's user into the mind of another person.
To activate it, the user needs to say "Ita!" while holding the ball from below, and the recipient needs to touch the ball at the same time. [Enchantment level 15]
The globus magnus imaginationis is a hollow metal ball the size of a medicine ball. It is enchanted with unlimited uses of the effect: Share Imagination With Many (CrMe base 4, R: Touch, D: Moment, T: Group), which allows to transfer an imagination of the ball's user into the mind of up to 10 other persons at once.
To activate it, the user needs to say "Ita!" while holding the ball from below, while each recipients needs to touch the ball - thereby identifying themselves as part of the T: Group. [Enchantment level 25]
Both items are simple Lesser Enchantments using common Arts, generally useful and not dangerous - so there might be many lab texts for them in circulation.
Some Jerbitons instead of balls use sculptures of fountains to enchant with the effects, calling such devices fons parva imaginationis and fons magna imaginationis.