Most knitters worry very little about row gauge. After all, most of the time we are concerned with how wide our work will be. How tall or short it becomes is pretty easy to control in most projects by just knitting more or fewer rows. But if you are combining different stitches across the same row, then row gauge can be an issue. If you have a stitch pattern that is short in the same row with a stitch pattern that is tall, then your fabric will not want to lie flat and will be prone to puckering. This can be a fascinating textural design element, but it can also just be a frumpy mess!
My concern in this circumstance is that the i-cord would be too short. So I added a yarn over in between the two i-cord knit stitches. Every row I dropped the yarn over and replaced it with a new one, but I never worked it. So I never turned it into a stitch. Its sole purpose was to put extra yarn in the i-cord so that those stitches would grow to the same height as the lace stitches.
The downside is that these stitches are a little long and gangly. If you don't like the look, you could instead work two rounds of i-cord at the edges. That would give you more rows, which means the height of the stitches could be less. Either way, be sure your row gauges are compatible!