Hello Bruno,

Sorry for the late reply, you could configure the text in,

JOOMLA\language\en-GB\en-GB.com_easyblog.ini

ehere en-GB is for english, find the languange file you are using and translate it from there.
to configure the email confirmation message is located in:

JOOMLA\components\com_easyblog\themes\default\email.subscriptions.confirmation.html.php

When subscription module is submitted the ajax that loads the form is in

JOOMLA\components\com_easyblog\themes\default\ajax.dialog.subscribe.php

you will need to add a javascript onclick redirect on line 65

<input type="button" value="<?php echo JText::_('COM_EASYBLOG_SUBSCRIBE');?>" class="button" id="edialog-submit" name="edialog-submit" onclick="eblog.subscription.submit('<?php echo $type;?>');" />

Hope that helps:)
If you need further assistance please give me your backend access and FTP.

Thanks:)