One of the coolest features I like about compiling my own firmware is that you can include the configuration files in the firmware, so out of the box the router is setup for how you need it.
My friend and I have almost identical routers from Linksys WRT series and I was going to make a firmware image for them using my pre-configured wireless config. However, our routers have different 'path/phy' options so initially their router's wireless failed to work.
According to the https://wiki.openwrt.org/doc/uci/wireless documentation the Phy (path for Mac80211l) is autodetected. With some testing I removed that option from my wireless configuration on my working router and also left it in but with no value to see if it would fill it in for me automatically. Unfortunately it just created a new radio2 below the rest of the config.
You can try "option phy phy0" instead; that will make it attach to the first wifi radio seen by the system. Alternatively, if the radio macs have the same OUI prefix, you could use a wildcard MAC address instead of option phy / option path: