I think it would be easier to provide a good response to this question if you provide us with an example of some YAML input that is not parsing correctly using a Perl YAML module, and then an example of the desired output. I don't know anything about PyYAML, and I've got plenty of other priorities on things I am interested in learning without spending time with it. Sample input, expected output, and actual output will save us research time by allowing us to leverage what you already know, adding to it those things that we already know.

It would be super helpful if we could see an example of the YAML being generated. YAML is YAML, if it's adhering to the YAML standard, there's no reason it can't be parsed by *any* YAML parser that also adheres to said standard.

Here is an example of a string I created in perl that reproduces one of the problems:

  $out = "Things:\n  - Name: thing_1\n    Sub:\n      key1: value1\n  
+    key2: very very very very very very very very very very very very
+ very very\n        long line wrapped value2\nkey3: value3\n";
[download]

When it prints out in the log, it looks like this:

Things:
  - Name: thing_1
    Sub:
      key1: value1
      key2: very very very very very very very very very very very ver
+y very very
        long line wrapped value2
key3: value3
[download]

If I paste this into yamlint it is valid, but the Loader complains:

YAML Error: Inconsistent indentation level
[download]

You want this?

#!/usr/bin/perl --
use strict; use warnings;
use YAML qw/ Load Dump /;
use Data::Dump qw/ dd /;
my $it = {
  Things => [
    {
      Name => "thing_1",
      Sub  => {
                key1 => "value1",
                key2 => "very very very very very very very very very 
+very very very very very long line\nwrapped value2",
                key3 => "value3",
              },
    },
  ],
};
dd( Dump( $it ) );
print Dump( $it ), "\n";
__END__
"---\nThings:\n  - Name: thing_1\n    Sub:\n      key1: value1\n      
+key2: |-\n        very very very very very very very very very very v
+ery very very very long line\n        wrapped value2\n      key3: val
+ue3\n"
---
Things:
  - Name: thing_1
    Sub:
      key1: value1
      key2: |-
        very very very very very very very very very very very very ve
+ry very long line
        wrapped value2
      key3: value3
[download]

How did you create the string? Why is your indentation level inconsistent? Perl module YAML also complains

YAML Error: Inconsistent indentation level
   Code: YAML_PARSE_ERR_INCONSISTENT_INDENTATION
   Line: 6
   Document: 1
[download]