"level of language proficiency" is a correct and usable phrase in written English.
It can be used to describe someone's level of proficiency or fluency in a particular language. Here is an example: "John's level of language proficiency in Spanish is remarkable, as he is able to speak, read, and write fluently after only a year of studying the language."
Students seeking to enroll in an overseas language program must be at the intermediate or advanced level of language proficiency.
Language Levels: Undergraduate and graduate students may only apply to study Intermediate or Advanced level of language proficiency.
PhD candidates applying for FLAS dissertation writing or dissertation research abroad must be already at the advanced level of language proficiency.
Students wishing to use an award for an overseas language program must be at the intermediate or advanced level of language proficiency.
Only students who are at the advanced level of language proficiency may propose to use a FLAS award for dissertation research.
The level of language proficiency among incoming students was much higher in Britain, France and Germany than in the Netherlands or Sweden, because the first three countries' languages are more commonly spoken around the world.
The letters they wrote at the very end of the semester showed a real improvement on all levels of language proficiency.
The Chi-square test showed no significant difference among learners at different levels of language proficiency.
The comparison of different levels of language proficiency showed that language learners increase their use of conventional expressions at higher levels of language proficiency requiring both linguistic and sociopragmatic competence.
Nonetheless, the One-way ANOVA test showed no significant difference among learners at different levels of language proficiency.
It is highly likely that a relatively large number of levels or sub-levels of language proficiency will be needed to cover this range.
