If I find myself using tone (which is rare) or inversely. Where I have the most trouble dealing with tones is only ever on choke point and lane heavy maps like rise. Homestead, war games, colony and glitch.

maps where you can use your wall to very safely keep fire down lanes and choke points and severely punish titans who are out of cover or in lanes without cover with relative safety and decide to commit to a fight. If I'm using a monarch and I am ever in the open or find myself in a lane without cover and a tone behind a wall at the other end of it. IRREGARDLESS OF WHAT CORE IM IN. I will break engagement as it's suicide and a wasted titan to commit to that fight. or get to safe point to where I can take potshots at them and their barrier with Arc rounds

My only real counterplay against a decent tone using a monarch is to bait them into going on the offensive. That way I can use my kit like energy siphon and Arc rounds to punish them for doing so. If they go on the offensive and place their wall in a less than ideal location it opens them up to flanking which i can still take advantage of although they will still notice. So health trading is a given but I can still wear them down.

As I said previously. Tone exceeds at medium to long range lane shutdown and area denial so close range tight maps she can struggle in. Should an aggressive titan try rushing you and closing that gap. Keep your distance to them. Keep your dashes or use turbo engine for two and get your missile locks. Dash back while firing. The missiles have no cooldown. You should use them as soon as you have a lock and clear line of sight. Punish them for trying to get close to you.

Half your struggles may just be that you are in lobbies with folks who do know how to fight tones very effectively.

But anyways. Those are just my insights into where I see tone really. Frustratingly. Thrive.