I have been hearing many times the pronunciation of La and some other sounds and don't understand yet, is it soft or solid? I don't know how to represent better this sound in English but if you in Ukrainian or Russian it sounds excellent - soft "ля" and solid "ла", you can check it via google translator. So, how does "La", not " L'.. " or "Le", exactly "La" should sound?
According to the page Comment prononcer les consonnes russes, the soft L can be heard in French.
Lèvre IPA [lɛvʁ] is reported to have a hard L and liège IPA [ljɛʒ] a soft L. Effectively, the position of the tongue during the L part is different when we pronounce these words.
The /j/ seems to affect the way the previous L is pronounced, which becomes slightly palatalized (in French, mouillé).
As there is no /j/ in La Fontaine, the /a/ in la then keeps the L hard.
However, Ла Фонтэн is unlikely to perfectly represent the right pronunciation given the fact there are no nasal vowels in Russian (here on is [ɔ̃]), but I guess for Russian ears, identifying this sound is as challenging as for ours dealing with soft and hard consonants.
When I ask GT to say in French "La Fontaine", the L is quite unnatural but more or less acceptable.
When I ask it to pronounce in Russian "ля фонтэн", the L is similar but the a is wrong, sound too close to a French e like Le Fontaine.
When I ask it to pronounce "ла фонтэн", the L is very wrong but the a is closer to the French one.
It's getting more interesting when I ask GT to pronounce :
Neither of the sequences are really acceptable, and the wider gap affects the vowels. On the other hand, the French la la la la la la is correctly reproducing the standard French pronunciation of the last four "la".
So if I trust GT, I'm afraid the Russian phonology isn't able to come near the French LA sound.
After switching from Russian to Ukrainian, ла ла ла sounds closer to the French pronunciation.