Were they inferior contraptions thrown up by backward western Confederates?
Most emphatically no. At least until Magruder arrived.
Magruder brought with him some of the same engineers who had worked on his fortifications on the Peninsula, namely Valery Sulakowski and Henry T. Douglas (who feuded with each other throughout the war). I'll list the credentials of engineers I know of who served the CS cause in Texas -
Sulakowski - officer in the Austrian army, civil engineer in New Orleans before the war
Douglas - civil engineer, variously serving on the staffs of Magruder, Kirby Smith, AP Hill, and GW Smith
Julius Kellersberg - civil and military engineer, also a former officer of the Austrian army, helped lay out the townsite of Oakland, California
Caleb G. Forshey - besides being a talented civil engineer and inventor, founded his own military academy in Galveston before the war
William H. Griffin - commanded his own 21st Texas Infantry Battalion and was an honors graduate of West Point in civil engineering
Theodore Heermann - prewar physician and civil engineer
Theodore Kosse - civil engineer
Richard M. Venable - civil engineer, graduate of Hampden-Sydney College, served on Kirby Smith's staff
None of these men were clueless about the siting, construction, and armament of fortifications.
There were works built by militia forces when the war started, such as Fort Sabine, or old, prewar, and obsolete earthworks such as Fort Point at Galveston, Fort Washington at the Matagorda Peninsula and south of Saluria, and the Town Redoubt at Velasco. But when some of the above-named engineers became responsible for defense of these areas, the fortifications became a thing for the Federals to reckon with. It's already been pointed out that the extensive, powerful fortifications at Caney Creek halted the further progress of US General Washburn up the Matagorda before the campaign was abandoned. However, the powerfully-built and well-armed Fort Esperanza (which replaced the earlier-mentioned Fort Washington) had to be abandoned during an attack by Washburn's forces in November 1863, as its guns all faced the Gulf and its landward defenses failed to stop the Federals.
This is the report from Kellersberg about the first fort at Sabine Pass, which was built by militiamen who had no experience in engineering or soldiering -
About 2 miles south of the town of Sabine, and on same side of the river, there is an earthwork thrown up not sufficient to protect the four guns that are in it. The shape and figure is also not according to the proper defense, the ground itself about 2 feet too low, and therefore subject to occasional overflow. The location itself is a good one, and has command over vessels that can cross the bar, which has about an average depth of 6 to 7 feet, with soft, muddy bottom. The armament consists of four guns, of which two are 32-pounders and two 18-pounders. All four are on old and unwieldy truck carriages. The powder magazine is not bombproof, and also subject to overflows. The whole work is in a dilapidated condition. There is ammunition enough for all four guns, but they have no fuses for shells, nor port-fires, neither gunners’ level, tangent scales, pass-boxes, friction-tubes, lanyards, &c.
This work was attacked by three US Navy ships on September 25, 1862, which blasted it out of the fort's range in the evening. During the night, the guns were spiked and fort was evacuated by the CS. One of the Federal skippers, Lewis W. Pennington (who had been a resident of Sabine Pass before the war), actually witnessed the soil thrown by the explosion of a shell bury a man who was standing in the works. This tells me that the soil used to build the parapet was not layered and tamped, and was not of the proper dimensions (the thickness and slope of properly engineered parapets would absorb incoming ordnance).
Kellersberg then recommended a plan to remedy these deficiencies, and he was immediately ordered to implement them -
About 3 to 5 miles up the river there are two 24-pounders on barbette carriages mounted on a shell bank. They are there of no use whatever, as there is a bar with but 3 feet of water at the mouth of Sabine River into Sabine Lake. No vessels of any amount can therefore go up to these guns. They can therefore be employed somewhere else. The pass at Sabine is certainly a very important point, and in fact the only port from where we receive our powder and other articles. It is the nearest point to the West Indies and easy of access. I would therefore recommend the erection of a strong open battery in place of the old one, for five guns (three of 32 and two of 24-pounders), all on barbette carriages. Then take those two 18-pounders and place them half way between the battery and the town, so that they may flank the lower works.
The strong, open battery he referred to became Fort Griffin, which was unfinished by the time of a much more powerful Federal attack, intended to be the vanguard of the invasion of Texas. The fort took the punishment of an all-day bombardment from four powerfully-armed gunboats, but when the gunboats attacked, the CS gunners disabled three with shots to their steam drums, capturing two of them and sending the rest of the force scrambling back to New Orleans.
When I say scrambling, I mean it literally.. several transport vessels, carrying the occupation force of about 5,000 men, collided with each other off the bar, and horses, mules, and provisions were thrown overboard to lighten the vessels so they could escape more quickly.
And of course, Fort Griffin was extensively strengthened, expanded, enlarged, and better-armed after the battle. The full transcript of Sulakowski's orders for this work is too extensive to post here. Fort Manhassett, a system of five redoubts and redans built over a mile of saltgrass prairie seven miles west of Sabine Pass, closed off the westward approach to Fort Griffin.
Piggybacking on JD Stevens's post on the Galveston fortifications, I'll add that on March 12, 1864, the city council of Galveston tendered their thanks to Sulakowski and Kellersberg, "
two distinguished engineers who have displayed such scientific and military skill in erecting defenses around the city and other vulnerable points on the gulf coast, which stand in bold defiance, now complete, to resist any force which our common enemy can bring to bear against us."
So at least in Texas, fortifications were every bit as well-built and dangerous as those anywhere else in the CSA.