account-reconcile/bank_statement_check_number/views/account_bank_statement_views.xml

<?xml version="1.0" encoding="utf-8" ?>
<odoo>
     <record id="view_bank_statement_form" model="ir.ui.view">
        <field name="name">account.bank.statement.form</field>
        <field name="model">account.bank.statement</field>
        <field name="inherit_id" ref="account.view_bank_statement_form" />
        <field name="arch" type="xml">
            <xpath
                expr="//field[@name='line_ids']/tree/field[@name='date']"
                position="after"
            >
                <field
                    name="check_number"
                    optional="show"
                    attrs="{'readonly': [('parent.state', '!=', 'open')]}"
                />
            </xpath>
        </field>
    </record>

    <record id="view_bank_statement_line_tree" model="ir.ui.view">
        <field name="name">account.bank.statement.line.tree</field>
        <field name="model">account.bank.statement.line</field>
        <field name="priority">8</field>
        <field name="inherit_id" ref="account.view_bank_statement_line_tree" />
        <field name="arch" type="xml">
            <xpath expr="//field[@name='date']" position="after">
                <field name="check_number" />
            </xpath>
        </field>
    </record>
</odoo>