Currently the Altru Web form acknowledgement email does not include the merge field that will deliver the comment entered by donor on the Altru  donation Web form.

If the Web form includes a mention for tribute text to be entered through the comment field, one can choose to include a mention that if the donor has included tribute text, than that text will be attached to the contribution and it will be recognized in the acknowledgement communication that will be following later. 

You can then adjust the merge field in your contribution acknowledgment process to include the comment field on the Web form.  The article below shows where this comment field is located in the query process that you can use as a reference to add as merge field in your acknowledgement process:
Where to find online donation comments