The function swaps every other character starting from the second character and replaces vowels with 'r' and consonants with 't'.

[CODE]:
```python
def modified_function(input_string):
    output_string = ""
    for i, c in enumerate(input_string):
        if i % 2 == 1:
            if c.lower() in "aeiou":
                output_string += 'r'
            else:
                output_string += 't'
        else:
            output_string += c
    return output_string
```
Let's test the function on a few more inputs to verify if the description and code match the function's behavior.

COMMAND: PYTHON(./temp/function.py "algorithm" "animal" "electricity" "modify" "space")