I honestly do find these suggestions to be a little messy and do not fully adress the underlying issues though with them mostly being aimed on adressing teamplay / quality of life issues it does mean that your impression of the issue is right on the money never the less!.
Limbo currently suffers from a mixture of 3 issues.
Poor team synergy:
Any player picking up limbo for the first time is bound to make a mess. Banished enemies left strewn about, Banished allies by random, Cataclysm + stasis + long range = Slowdown.
He is also currently clunky with some of his more powerful moves which means that for all practical purpose's the banish + mesa peacemaker(immortal mesa) combo is limited to premade levelcap squads and not general usage.
Old bugs/Old Nerfs and Inconsistency.
Limbo is an old warframe and one notorious for breaking the game in one form or another and so weather by Patchwork intervention or just entropy he has accumulated bug.
One of limbo's main jobs to give an example is to defend targets. Be it NPC or objective. Coil drives in Fortuna cant be affected by abilities and so not even cataclysm can defend them from incoming fire. In the Deimos arcana bounties Juggernauts cant be banished more than once because of ability resistance. If cataclysm is up and a void angel disables your warframe you have to now wait for cataclysm to expire before you can shoot your self free. Same issue with the last gasp ability from Unairu. Enemies/ Environmental effects piercing the rift the rift when they shouldn't, So on.
Poor visual Language
The rift is terrible at communicating what it does to the player upfront. You got to do rather extensive research and not fall into one of the myriad noobtraps and bugs along the way at the same time. Fx long range limbo builds being the first thing people turn to or suddenly getting deleted when you thought your self safe. The result is a rather terrible experience and combine that with limbo being an advanced warframe with abilities that demand the player to be able to read the battlefield to make the most use off it and you got a recipe for a lot of players simply writing the frame off. Regardless of how powerful it is.
My personal solution to limbo.
1. Address the team synergy issue by streamlining and ironing out some of the kinks.
The frame already works more or less with exception of CC slowing missions down which is a can of worms that DE will have to address separately I'm afraid but what can be done is ensure the rift at least does not get in the way of allies, regardless of how much mess an unskilled limbo player makes.
My Suggestion here is to hand out limbo's passive to people via a relatively easily attainable method. By handing out Limbo's passive while limbo is in the squad we essentially remove the main issue of players not being able to shoot rifted targets there and then! All you need to do is just know its in the rift and dodge in to get it killed simple as that. The main part is that the buff needs to be easily atainable and the player has to be able to control the rift them selfs not waiting for limbo to grant them access or leave.
Balance of this is entirely on DE's side though. Weather or not they want it to be reduced duration one can remain in the rift as an ally or what other consideration they want to take.
2. SPRING CLEANING.
A look through limbo and updating his ruleset to reach more consistent results by removing old nerfs old bugs and potentially even making cataclysm able to drag ability immune enemies into it( Some issues may arise from this and will need its own separate adjustments) Operator Rift interactions fix. So on.
3. Getting limbo To teach himself better.
This is where the improved visaual language comes in but i admitedly am no expert here. What i would personally do however is ensure that the rift visuals are clearly distinguishing between shootable and non shootable targets WITHOUT falling into the trap of the pre rework limbo of visual clutter. This visual upgrade should also aim to communicate clearly weather or not an aly got a target available to shoot at.