Slack alerts into Webex Team

Question

I'm trying to migrate Prometheus Alertmanager alerting from using slack_configs (ref1) into the webex_configs (ref2). Is there any possibility to adjust the message sent to Webex with structure used in "old" slack_configs? Following structure is needed:

<Title composed of .Status + text eg 'Event Notification'>
Alert - < Annotations.Summary + Labes.severity >
Message - < Annotations.message >
Graph - < GeneralURL >, Dashboard < Annotations.dashboardurl >
Details ( composed of Labels.SortedPairs (Name + Value))

I know this is possible via webhook_configs + proxy, however If there's possibility to create this without the need of proxy, that would be ideal.
- ref1

- name: alerts
        slack_configs:
          - api_url: https://hooks.slack.com/services/XXXXXXXXXXXXXXXXXXXXXXXXXXXXX
            channel: '#XXXXXXXXXXXXXXXXXXXXXXXXXXXXX'
            http_config:
              proxy_url: XXXXXXXXXXX
            text: |-
              {{ `{{ range .Alerts }}
                *Alert:* {{ .Annotations.summary }} - {{ .Labels.severity }}
                *Message:* {{ .Annotations.message }}
                *Graph:* <{{ .GeneratorURL }}|:chart_with_upwards_trend:> *Dashboard:* <{{ .Annotations.dashboardurl }}|:bar_chart:>
                *Details:*
                {{ range .Labels.SortedPairs }} • *{{ .Name }}:* {{ .Value }}
                {{ end }}
              {{ end }}` }}
            title: |-
              {{ `[{{ .Status | toUpper }}{{ if eq .Status "firing" }}:{{ .Alerts.Firing | len }}{{ end }}] Notification` }}

- ref2

- name: alerts_webex
        webex_configs:
          - api_url: 'https://webexapis.com/v1/messages'
            room_id: 'XXXXXXXXXXXXXXXXXXXXXXXXXXXXX'
            send_resolved: false
            http_config:
              proxy_url: XXXXXXXXXXXXXXXXXXXXXXXXXXXXX
              authorization:
                type: 'Bearer'
                credentials: 'XXXXXXXXXXXXXXXXXXXXXXXXXXXXX'
            message: |-
              {{ `{{ range .Alerts }}
                "**{{ .Status }}{{ if eq .Status "firing" }}:{{ .Alerts.Firing | len }}{{ end }} Notification**\n\n*Severity:* {{ .Labels.severity }}\n**Alert:** {{ .Annotations.summary }}\n**Message:** {{ .Annotations.message }}\n**Graph:** [Graph URL]({{ .GeneratorURL }})\n**Dashboard:** [Dashboard URL]({{ .Annotations.dashboardurl }})\n**Details:**\n{{ range .Labels.SortedPairs }} • **{{ .Name }}:** {{ .Value }}\n{{ end }}"
              {{ end }}` }}

Note: Alerts from webex_configs don't arrive at any point, without any errors produced & connection working fine. slack_configs fully functional, even when using both configurations together with routes & continue: true for receivers, only slack receives the alert.