Win8 Strawberry 5.30.3.1 (64)  Wed 09/07/2022  8:14:56
C:\@Work\Perl\monks
>perl

use 5.010;  # needs \K regex extension

use strict;
use warnings;

# use Data::Dump qw(dd);  # for debug

my $j = <<'EOJ';
"device\"": [{"host_in}fo"  :  { "eng{ine_id,":null   ,
"name:": null   ,"host_group_info\\" :{"na\"me":null,"\"remarks":null
,
    "id" : 0 } "{[:,"  :  "weird", "crazy"  :  "[{,:" }}
  ]
EOJ
print ">>\n$j<< \n";

use constant DENT => '    ';
my $n_dent = 0;

my %pretty = (
    '{' => sub { my $d = DENT x ++$n_dent;  return "$_[0]\n$d";     },
    '}' => sub { my $d = DENT x --$n_dent;  return "\n$d$_[0]\n$d"; },
    ',' => sub { my $d = DENT x   $n_dent;  return "$_[0]\n$d";     },
    ':' => sub { my $d = DENT x   $n_dent;  return "$_[0] ";        },
    );

my $rx_d_quote = qr{ " [^\\"]* (?: \\. [^\\"]*)* " }xms;

$j =~ s{ $rx_d_quote? \K \s* ([{},:]) \s* }
       { $pretty{$1}->($1) }xmsge;
print ">>\n$j<< \n";

^Z
>>
"device\"": [{"host_in}fo"  :  { "eng{ine_id,":null   ,
"name:": null   ,"host_group_info\\" :{"na\"me":null,"\"remarks":null
,
    "id" : 0 } "{[:,"  :  "weird", "crazy"  :  "[{,:" }}
  ]
<<
>>
"device\"": [{
    "host_in}fo": {
        "eng{ine_id,": null,
        "name:": null,
        "host_group_info\\": {
            "na\"me": null,
            "\"remarks": null,
            "id": 0
        }
        "{[:,": "weird",
        "crazy": "[{,:"
    }

}
]
<<