IIRC, OpenRAM uses the high time of the clock cycle to precharge. Would it be possible to instead detect the rising edge of clock (like creating a delayed version of the clock through a delay line and comparing it with clk) to just generate a short pre-charge pulse at the beginning of the cycle ?

It would be possible and this is a welcome addition, however it is very sensitive to process and needs to be tuned and verified. We have generally avoided it for that reason.

Yeah, I'd imagine for a first attempt it would need to be made configurable for testing. (possibly having a fallback mode to using the full clk high cycle).