SMART values normally do not "reset" in the normal sense of the word (get set back to zero due to some event, such as a drive power-on event). An error count can, however, decrease, if the condition that caused the error count to be increased no longer exists. There are a few exceptions, but UDMA CRC Error Count is not one of them.
I'm not really sure what you mean with "if this value is actual", but if you mean what I think you mean, then it follows from the above that the reported value will be the total value for the disk's life time.
So what you should be looking for is error count increments. A value holding steady means that particular aspect of the hard disk drive is stable, as far as the SMART monitoring can determine and report. (That is "stable" in the medical sense of the word; remember a patient may be for example stable but still in critical condition, which is very different from stable and healthy. SMART monitoring can work the same way. Suppose attribute 0x05 Reallocated Sectors Count is holding steady at the maximum allowed value; no further reallocations are possible, because the drive has run out of spare sectors, but that particular attribute won't indicate any further deterioration. Attribute 0xC6 Offline Uncorrectable might still indicate deterioration, however.)