CKAN - adding custom fields with ckenxt-scheming - dataset

Question

i'm working with ckanext-scheming and trying to add a custom field similar to repeating subfields with few modifications (below are few files that define the field and it's behavior), for the most part it works correct but it doesn't get submitted to the database (although once i intercept the package create action, i can see the field data is there), any ideas are welcomed:
the scheming yaml part:
- field_name: tag_string
label: Tags
form_snippet: custom_tags.html
display_snippet: modified_repeating_subfields.html
help_text: >-
Additional keywords useful for ...
the form snippet:
{% import 'macros/form.html' as form %}
{% asset 'ckanext-dalrrdemcdcpr/facets-active-js' %}
{%
set options=[
{'value': '001', 'text': _('Discipline')}
, {'value': '002', 'text': _('Place')}
, {'value': '003', 'text': _('Stratum')}
, {'value': "004", "text":_("Temporal")}
, {'value': "005", "text":_("Theme")}
]
%}
{%- set extra_html = caller() if caller -%}
{% set classes = (classes|list) %}
{% call form.input_block(field.field_name, field.label, "", classes, extra_html=extra_html, is_required=false) %}
<div class="repeating_custom_tag_row-index-0" id="repeating_custom_tag_row-index-0" data-module="repeating_tags_handler">
<div class="metadata_tags_holder">
<div class="metadata_tags_styler">
<div class="metadata_tags_input">
<label for="custom_delete" class="input-group-text">{{ _('Input tag') }}</label>
<input class="form-control" id="repeating_custom_tag_row-index0-tag-input-index-0" type="text" name="repeating_custom_tag_row-index0-tag-input-index-0" value="" placeholder=""/>
</div>
<div class="metadata_tags_type_select">
<div><label for="tag_select" class="input-group-text">{{_('Input tag type')}}</label></div>
<select id="tag_select" name="repeating_custom_tag_row-index0-select-input-index-0" required>
{% for option in options %}
<option value="{{ option.value }}"{% if option.value == selected %} selected{% endif %}>{{ option.text or option.value }}</option>
{% endfor %}
</select>
</div>
<div class="tags_buttons_wrapper">
<div class="tags_handling_buttons">
<button class="btn btn-success add_metadata_tags_btn">Add</button>
<button class="btn btn-danger remove_metadata_tags_btn"><i class="fa fa-trash"></i>Remove</button>
</div>
</div>
</div>
</div>
</div>
{% endcall %}
the display snippet (don't think it's useful):
{% set fields = data[field.field_name] %}
{% block subfield_display %}
{% for field_data in fields %}
<div class="panel panel-default">
<div class="panel-body">
<dl class="scheming-subfield-list">
{% for subfield in field.repeating_subfields %}
<dt class="dataset-label">
{{ h.scheming_language_text(subfield.label) }}
</dt>
<dd>
{%- snippet 'scheming/snippets/display_field.html',
field=subfield,
data=field_data,
entity_type=entity_type,
object_type=object_type
-%}
</dd>
{% endfor %}
</dl>
</div>
</div>
{% endfor %}
{% endblock %}
this is how the relevant part of the form looks (the tags):
the js module controlling tags fields behavior:
ckan.module("repeating_tags_handler", function ($){
/*
control muliple interaction regarding the tags
section, handles both css and buttons behavior.
*/
return {
initialize: function(){
$.proxyAll(this,/_on/);
// set the styles before copying the section
let add_btns = $(".add_metadata_tags_btn")
add_btns.each((idx,add_btn) => {add_btn.style.marginRight="2px"})
$(document).on('click','.add_metadata_tags_btn',this._on_add_tags)
$(document).on('click','.remove_metadata_tags_btn',this._on_remove_tags)
let repeating_fields_wrapper = $(".repeating_custom_tag_row-index-0")
repeating_fields_wrapper.css({"margin-bottom":"30px"})
let tags_holder = $(".metadata_tags_holder")
tags_holder.css("width:100%")
$(".metadata_tags_styler").css({"width":"100%", "display": 'flex', 'flex-direction': 'row'})
$(".metadata_tags_input").css({"width":"40%"})
$(".metadata_tags_type_select").css({"width":"30%"})//tag_select
$("#tag_select").css({"width":"100%", "height":"34px", "margin-left":"4px"})
$(".tags_buttons_wrapper").css({"margin-left": "4px", "padding-top": "2px"})
$(".tags_handling_buttons").css({"width":"100%","padding-top":"22px", "display": "flex", "flex-direction": "row", "margin-left":"4px"})
this.section_html = tags_holder.html()
const config = { attributes: true, childList: true, subtree: true };
//const added_items_observer = new MutationObserver(this.added_items_mutation_observer);
//added_items_observer.observe(repeating_fields_wrapper.get(0), config)
},
_on_add_tags:function(e){
e.preventDefault()
//let search_parent = e.target.parentElement.parentElement.parentElement.parentElement
let search_parent = e.target.closest(".metadata_tags_styler")
let new_index = Array.from(search_parent.parentNode.children).indexOf(search_parent) +1
let new_index_text = `index-${new_index}`
this.section_html = this.section_html.replace(/index-[0-9]/g, new_index_text)
this.el.append(this.section_html)
},
_on_remove_tags:function(e){
e.preventDefault()
let removed_tag_row = e.target.closest(".metadata_tags_styler")
//let removed_tag_row = e.target.parentElement.parentElement.parentElement.parentElement
removed_tag_row.remove()
},
}
})
and finally this is a Runtime error screenshot i raised for you - dear - to see the tags data is there:
thank you!