As a WFT main myself (and a former R.O.B. user), I know that her zoning capabilities can definitely contend with yours. Always be on the lookout for any soccer balls she sends your way, it's a lot easier to get nicked by those than you'd think. Just stick to the usual gameplan of throwing out gyros and lasers to wall her out
WFT is also not someone you want to get close to on the ground unless your character is specifically suited for rushdown. If you get buried by her jab then there is a lot of nasty stuff that can potentially happen to you. Be especially careful when at high percentages, her F-Tilt (even without Deep Breathing) is deceptively powerful. You don't really have to worry about F-Smash or U-Smash imo since they're really unsafe and should only be used for hard reads. D-Smash, however, can easily catch you off guard. It has a lot of horizontal knockback, which means you'll have to spend more time getting back to stage, which is not good against WFT given your recovery. But since R.O.B. isn't meant to be an up close fighter in the first place, you probably won't have to worry about this. Just keep your distance and try not to get in her face.
In the air you generally don't want try to challenge WFT as her go-to aerials outspeed yours quite a bit. If you find yourself in a tight spot, Fair or a pre-emptive Nair will be your best bet.
The only place where I would say WFT absolutely walks all over R.O.B. is offstage. With Three Spikes, a projectile that can be incredibly useful for gimping, and a great recovery, WFT is the Offstage Queen. If you find yourself offstage, get ready for soccer balls and an unusually aggro side of this character. The best thing you can do if she goes for a spike is either an air dodge or a Uair. Just be very careful, if you get knocked around too much you'll be out of fuel for your Up B before you know it.
Now the edge R.O.B. has in this matchup is WFT's inability to handle constant pressure. If a WFT finds themself in a tight spot it will be absolute hell for them to return to the neutral. So with R.O.B., you just do what you do best; Make an impenetrable wall of Gyros and Lasers and keep her on her toes, as that's the only way to really catch this character off-balance.
Personally I think this match up is pretty even. It could be 55-45 in either direction depending on your experience, I suppose.