I am new junior developer and learning apex and could someone review my code and comment on it ?
This is my first api response class. Any tips and tricks ? what is wrong and what is good ?

public with sharing class PostiApiResponseHandler {

private final static PostiRegisterService REGISTER_SERVICE = new PostiRegisterService();
private final static PostiProcessingLogSelector LOG_SELECTOR = new PostiProcessingLogSelector();

public static void parseResponse(String responseBody) {
    Map<String, Object> response = deserializeResponse(responseBody);
    logOperationStatus(response);
    Map<String, Object> message = getMessage(response);
    logMessageDetails(message);

    if (isValidMessage(message)) {
        ProcessingLogData logData = extractProcessingLogData(message);
        processResponseMessage(logData, message);
    }
}

private static Map<String, Object> deserializeResponse(String responseBody) {
    return (Map<String, Object>) JSON.deserializeUntyped(responseBody);
}

private static void logOperationStatus(Map<String, Object> response) {
    System.debug('Operation Status: ' + response.get('operationStatus'));
}

private static Map<String, Object> getMessage(Map<String, Object> response) {
    return (Map<String, Object>) response.get('message');
}

private static void logMessageDetails(Map<String, Object> message) {
    System.debug('Register ID: ' + message.get('id'));
    System.debug('Status: ' + message.get('status'));
    System.debug('Is Approved: ' + message.get('isApproved'));
    System.debug('Last Processing ID: ' + message.get('lastProcessingId'));
    System.debug('Last Processing Date: ' + message.get('lastProcessingDate'));
}

private static boolean isValidMessage(Map<String, Object> message) {
    return message != null && message.containsKey('id') && message.containsKey('lastProcessingDate') && message.containsKey('lastProcessingId');
}

private static ProcessingLogData extractProcessingLogData(Map<String, Object> message) {
    Datetime lastProcessingDate = Datetime.valueOf((String) message.get('lastProcessingDate'));
    String lastProcessingId = (String) message.get('lastProcessingId');
    String registerId = (String) message.get('id');

    return new ProcessingLogData(registerId, lastProcessingDate, lastProcessingId);
}

private static void processResponseMessage(ProcessingLogData logData, Map<String, Object> message) {
    Posti_Processing_Log__c storedLog = LOG_SELECTOR.getLogByRegisterId(logData.registerId);

    if (isNewProcessingData(logData.lastProcessingDate, logData.lastProcessingId, storedLog)) {
        List<Map<String, Object>> updates = (List<Map<String, Object>>) message.get('updates');
        processUpdates(updates, logData.registerId);
        upsertProcessingLog(storedLog, logData);
    }
}

private static boolean isNewProcessingData(Datetime lastProcessingDate, String lastProcessingId, Posti_Processing_Log__c storedLog) {
    return storedLog == null || lastProcessingDate > storedLog.Last_Processing_Date__c || !lastProcessingId.equals(storedLog.Last_Processing_Id__c);
}

private static void processUpdates(List<Map<String, Object>> updates, String registerId) {
    for (Map<String, Object> updateItem : updates) {
        Datetime processingDate = Datetime.valueOf((String) updateItem.get('processingDate'));
        List<Map<String, Object>> deliverables = (List<Map<String, Object>>) updateItem.get('deliverables');
        UpdateData updateData = new UpdateData(processingDate, deliverables);
        processDeliverables(updateData, registerId);
    }
}

private static void processDeliverables(UpdateData updateData, String registerId) {
    for (Map<String, Object> deliverable : updateData.deliverables) {
        if ('RESULT_JSON_FILE_CHANGES'.equals(deliverable.get('deliverableType'))) {
            String deliverableId = (String) deliverable.get('id');
            Integer numberOfChunks = Integer.valueOf((String) deliverable.get('numberOfChunks'));
            PostiRegisterService.downloadDeliverableFiles(registerId, deliverableId, numberOfChunks);
        }
    }
}

private static void upsertProcessingLog(Posti_Processing_Log__c storedLog, ProcessingLogData logData) {
    if (storedLog != null) {
        if (!Schema.sObjectType.Posti_Processing_Log__c.fields.Last_Processing_Date__c.isUpdateable() || 
            !Schema.sObjectType.Posti_Processing_Log__c.fields.Last_Processing_Id__c.isUpdateable()) {
            throw new System.DmlException('Insufficient access rights to update Posti_Processing_Log__c');
        }
        storedLog.Last_Processing_Date__c = logData.lastProcessingDate;
        storedLog.Last_Processing_Id__c = logData.lastProcessingId;
        update storedLog;
    } else {
        if (!Schema.sObjectType.Posti_Processing_Log__c.isCreateable()) {
            throw new System.DmlException('Insufficient access rights to create Posti_Processing_Log__c');
        }
        storedLog = new Posti_Processing_Log__c();
        storedLog.External_Id__c = logData.registerId;
        storedLog.Last_Processing_Date__c = logData.lastProcessingDate;
        storedLog.Last_Processing_Id__c = logData.lastProcessingId;
        insert storedLog;
    }
}

public static void processDownloadResponse(String responseBody) {
    Map<String, Object> response = (Map<String, Object>) JSON.deserializeUntyped(responseBody);
    List<Map<String, Object>> records = (List<Map<String, Object>>) response.get('records');

    for (Map<String, Object> record : records) {
        String customerId = (String) record.get('customerId');
        Map<String, Object> details = (Map<String, Object>) record.get('details');
        Map<String, Object> personStatus = (Map<String, Object>) details.get('personStatus');
        Map<String, Object> changes = (Map<String, Object>) record.get('changes');

        if ('2'.equals(personStatus.get('sPersonStatusCode'))) {
            PostiAccountUpdater.updateDeceasedStatus(customerId);
        } else {
            if (changes != null) {
                PostiAccountUpdater.updateAccount(customerId, changes);
            }
        }
    }
}

}

Im just looking for some experienced person validation for my code