You need to correct these lines in your code -

1.) 'amount' : 1000 (colon is missing) --- You can use an editor like VS code. It's a good practice and highly recommended. If you will write this code on Vs code editor, you will easily get to know all the syntax error your code has.

2.) filterval is an array and not an Object. So you don't have to use Object.keys. You can use map() directly on filterval.

filterval.map(() => {}) 

Do checkout console.log(Object.keys(filterval)) --- It will print an array of indexes. https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object/keys

3.) data.splice(index, 1) --- splice should be used on arrays and not on object. It should be filterval.splice(index, 1).
https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/splice

I would recommend that before using any built in methods of JavaScript, do refer MDN docs. Also, it's a good practice to break down your code into smaller chunks and keep checking at every step, if everything is going on right or not. If everything seems fine then move to the next step. If something's wrong then correct it and then move ahead.

Here's the code that fulfills the purpose.

let filterval = [
{
    'tran_type': "cs+",
    'date': "2/2/2022",
    'amount' : 10000
},
{
    'tran_type': "cs-",
    'date': "2/2/2022",
    'amount' : 10000
},
{
    'tran_type':"cs+",
    'date': "3/2/2022",
    'amount' : 20000
},
{
    'tran_type': "opo",
    'date': "2/2/2022",
    'amount' : 10000
},
{
    'tran_type': "opi",
    'date': "2/2/2022",
    'amount' : 10000
},
{
    'tran_type': "cs+",
    'date': "1/2/2022",
    'amount' : 70000
},
{
    'tran_type': "opo",
    'date': "1/2/2022",
    'amount' : 90000
}]



filterval.forEach((data1, index1) => {
    switch (data1.tran_type) {
        case 'cs+' :             
            removeIfFound(data1, index1, 'cs-')
            break;

        case 'cs-' :
            removeIfFound(data1, index1, 'cs+')
            break;

        case 'opo' :
            removeIfFound(data1, index1, 'opi')
            break;

        case 'opi' :
            removeIfFound(data1, index1, 'opo')
            break

        default : 
            break
    }
  })

  function removeIfFound(data1, index1, trans_type) {
    filterval.forEach((data2, index2) => {
        
        if (data2.tran_type === trans_type && checkIfEqual(data1, data2)) {
            filterval.splice(index1, 1)
            filterval.splice(index2 - 1, 1) 
            return
        }
    })
  }

  function checkIfEqual(data1, data2) {
    return (data1.date === data2.date) && (data1.amount === data2.amount)
  }

  console.log(filterval)

Let me know in case you need any explanation.

Change :

if(data.tran_type = 'cs+'){

code above always return true because you are giving data.tran_type value of 'cs+' to

if(data.tran_type == 'cs+'){

and also

'amount' 10000 //should be :
'amount': 10000 // you don't have ':'

and this code is checking if data.tran_type is equal to the value of 'cs+'.

and try to write your logic better, having so much ifs one inside another is very bad practice, it is difficult to read and see what the code does, try to make smaller functions which you call if some condition is accomplished.

Soooo, I broke your code in chunks and got the result you were asking for, this is not the best-looking code, but I wrote it so you can go through it and try to understand it

let array = [
  {
    tran_type: "cs+",
    date: 2 / 2 / 2022,
    amount: 10000,
  },
  {
    tran_type: "cs-",
    date: 2 / 2 / 2022,
    amount: 10000,
  },
  {
    tran_type: "cs+",
    date: 3 / 2 / 2022,
    amount: 20000,
  },
  {
    tran_type: "opo",
    date: 2 / 2 / 2022,
    amount: 10000,
  },
  {
    tran_type: "opi",
    date: 2 / 2 / 2022,
    amount: 10000,
  },
  {
    tran_type: "cs+",
    date: 1 / 2 / 2022,
    amount: 70000,
  },
  {
    tran_type: "opo",
    date: 1 / 2 / 2022,
    amount: 90000,
  },
];

let finalArray = [];

let csPositive = [];
let csNegative = [];
let opo = [];
let opi = [];

array.map((element) => {
  sortByType(element);
});

function sortByType(element) {
  sortCsPositive(element);
  sortCsNegative(element);
  sortOpo(element);
  sortOpi(element);
}

function sortCsPositive(element) {
  if (element.tran_type == "cs+") {
    csPositive.push(element);
  }
}
function sortCsNegative(element) {
  if (element.tran_type == "cs-") {
    csNegative.push(element);
  }
}
function sortOpo(element) {
  if (element.tran_type == "opo") {
    opo.push(element);
  }
}
function sortOpi(element) {
  if (element.tran_type == "opi") {
    opi.push(element);
  }
}

function compareDateAndAmout(oneArray, secondArray) {
  oneArray.forEach((x) => {
    secondArray.forEach((y) => {
      y.date == x.date && x.amout == y.amout ? "" : finalArray.push(x);
    });
  });
}

compareDateAndAmout(opo, opi);
compareDateAndAmout(csPositive, csNegative);
console.log(finalArray);