Echo doesn't make any linguistic remarks, physically or mentally, unless Conrad reaches out, but the feeling of their presence is strong while he's preparing Read Magic, and to a lesser degree during his calisthenics, ideas and information emanating from Them.
Conrad has an invocation now! It's quite basic, but by saying "Thank you, Lord Echo" he can allow Echo to speak physically. There are numerous potential avenues for this invocation to be augmented or evolved. The exact phrasing of the invocation can be changed, nuance can be added to the pronunciation of the invocation to allow for fine-grained control of the effect. The length, volume, language, point of origin, and direction of Echo's resultant speech can all be change, along with countless other variables.
The flow of the invocation could be reversed, such that instead of producing speech Echo will instead bring sounds to Conrad's ear, which could then be altered into something usable for eavesdropping and perhaps even long-range reconnaissance eventually.
These are only a small fraction of the total possibilities, though through the interface of Echo the breadth of the possibility space is not so daunting.
Echo's interest seems to linger especially on the mental object of Conrad's prepared Read Magic, before a new idea emerges.
It would require a greater amount of time and effort to reach from his current invocation, but with rearrangement it could be that, as long as Read Magic is prepared, Conrad could speak his invocation to be able to 'read' inscriptions, deciphering their function at a glance, and could expend a spell slot containing Read Magic to copy an observed inscription into the same mental space, allowing him to study it freely without need of the physical form.
This invocation's potential for future development is rich, including such possibilities as developing a broader eidetic memory, the ability to recreate copied inscriptions exactly, or perhaps even to 'translate' copied transcriptions into spells of arcane magic.