As you can see, it uses the "T" variable - turns remaining of an effect - in the expression and then explicitly applies "ceil" to it.
Based on that expression, I see no evidence that it "calculates the numeric modifier based on having 1 turn of the effect".
But yes, it "performs a ceiling to the nearest integer".
That is an issue with those particular modifier expressions, not a general issue with "Numeric modifier always returns integer value".
If you did not intend to generalize, perhaps you could have said "Orange Crusher modifiers always return integer value"?