FLeX: Fourier-based Low-rank EXpansion for multilingual transfer

Researchers propose FLeX, a parameter-efficient fine-tuning approach combining LoRA, advanced optimizers, and Fourier-based regularization to enable cross-lingual code generation across programming languages. The method achieves 42.1% pass@1 on Java tasks compared to a 34.2% baseline, demonstrating significant improvements in multilingual transfer without full model retraining.