The battery is only useful in command stuff for dropouts going across switches and/or dirty track as a rule. Frequently, the tender with the sound system drops the sound even though the locomotive continues, that's when the battery comes in handy. If you don't have those issues, you don't need a battery for command only use. I have some steamers that drop sound regularly, others seem to be fine. If nothing shows up checking rollers and wiring, I add the battery. I happen to have lots of them here.
All our TMCC engines restart chuffing after a sound drop out over a switch in Command mode. Sadly the new Legacy steamers we have are the ones which required your YLB Battery replacement because they do not restart the sounds after dropping out. I'm sure it is a bad Lionel software revision which causes this, quite a setback of design.